Miniscript: type system, script creation, text notation, tests

More information about Miniscript can be found at https://bitcoin.sipa.be/miniscript/ (the
website source is hosted at https://github.com/sipa/miniscript/).
This commit defines all fragments, their composition, parsing from
string representation and conversion to Script.

Co-Authored-By: Antoine Poinsot <darosior@protonmail.com>
Co-Authored-By: Sanket Kanjalkar <sanket1729@gmail.com>
Co-Authored-By: Samuel Dobson <dobsonsa68@gmail.com>

2 files changed, 1315 insertions, 0 deletions

diff --git a/src/script/miniscript.cpp b/src/script/miniscript.cpp
new file mode 100644
index 0000000000..8074be6cde
--- /dev/null
+++ b/src/script/miniscript.cpp
@@ -0,0 +1,295 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <string>
+#include <vector>
+#include <script/script.h>
+#include <script/miniscript.h>
+
+#include <assert.h>
+
+namespace miniscript {
+namespace internal {
+
+Type SanitizeType(Type e) {
+    int num_types = (e << "K"_mst) + (e << "V"_mst) + (e << "B"_mst) + (e << "W"_mst);
+    if (num_types == 0) return ""_mst; // No valid type, don't care about the rest
+    assert(num_types == 1); // K, V, B, W all conflict with each other
+    bool ok = // Work around a GCC 4.8 bug that breaks user-defined literals in macro calls.
+        (!(e << "z"_mst) || !(e << "o"_mst)) && // z conflicts with o
+        (!(e << "n"_mst) || !(e << "z"_mst)) && // n conflicts with z
+        (!(e << "n"_mst) || !(e << "W"_mst)) && // n conflicts with W
+        (!(e << "V"_mst) || !(e << "d"_mst)) && // V conflicts with d
+        (!(e << "K"_mst) ||  (e << "u"_mst)) && // K implies u
+        (!(e << "V"_mst) || !(e << "u"_mst)) && // V conflicts with u
+        (!(e << "e"_mst) || !(e << "f"_mst)) && // e conflicts with f
+        (!(e << "e"_mst) ||  (e << "d"_mst)) && // e implies d
+        (!(e << "V"_mst) || !(e << "e"_mst)) && // V conflicts with e
+        (!(e << "d"_mst) || !(e << "f"_mst)) && // d conflicts with f
+        (!(e << "V"_mst) ||  (e << "f"_mst)) && // V implies f
+        (!(e << "K"_mst) ||  (e << "s"_mst)) && // K implies s
+        (!(e << "z"_mst) ||  (e << "m"_mst)); // z implies m
+    assert(ok);
+    return e;
+}
+
+Type ComputeType(Fragment nodetype, Type x, Type y, Type z, const std::vector<Type>& sub_types, uint32_t k, size_t data_size, size_t n_subs, size_t n_keys) {
+    // Sanity check on data
+    if (nodetype == Fragment::SHA256 || nodetype == Fragment::HASH256) {
+        assert(data_size == 32);
+    } else if (nodetype == Fragment::RIPEMD160 || nodetype == Fragment::HASH160) {
+        assert(data_size == 20);
+    } else {
+        assert(data_size == 0);
+    }
+    // Sanity check on k
+    if (nodetype == Fragment::OLDER || nodetype == Fragment::AFTER) {
+        assert(k >= 1 && k < 0x80000000UL);
+    } else if (nodetype == Fragment::MULTI) {
+        assert(k >= 1 && k <= n_keys);
+    } else if (nodetype == Fragment::THRESH) {
+        assert(k >= 1 && k <= n_subs);
+    } else {
+        assert(k == 0);
+    }
+    // Sanity check on subs
+    if (nodetype == Fragment::AND_V || nodetype == Fragment::AND_B || nodetype == Fragment::OR_B ||
+        nodetype == Fragment::OR_C || nodetype == Fragment::OR_I || nodetype == Fragment::OR_D) {
+        assert(n_subs == 2);
+    } else if (nodetype == Fragment::ANDOR) {
+        assert(n_subs == 3);
+    } else if (nodetype == Fragment::WRAP_A || nodetype == Fragment::WRAP_S || nodetype == Fragment::WRAP_C ||
+               nodetype == Fragment::WRAP_D || nodetype == Fragment::WRAP_V || nodetype == Fragment::WRAP_J ||
+               nodetype == Fragment::WRAP_N) {
+        assert(n_subs == 1);
+    } else if (nodetype != Fragment::THRESH) {
+        assert(n_subs == 0);
+    }
+    // Sanity check on keys
+    if (nodetype == Fragment::PK_K || nodetype == Fragment::PK_H) {
+        assert(n_keys == 1);
+    } else if (nodetype == Fragment::MULTI) {
+        assert(n_keys >= 1 && n_keys <= 20);
+    } else {
+        assert(n_keys == 0);
+    }
+
+    // Below is the per-nodetype logic for computing the expression types.
+    // It heavily relies on Type's << operator (where "X << a_mst" means
+    // "X has all properties listed in a").
+    switch (nodetype) {
+        case Fragment::PK_K: return "Konudemsxk"_mst;
+        case Fragment::PK_H: return "Knudemsxk"_mst;
+        case Fragment::OLDER: return
+            "g"_mst.If(k & CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG) |
+            "h"_mst.If(!(k & CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG)) |
+            "Bzfmxk"_mst;
+        case Fragment::AFTER: return
+            "i"_mst.If(k >= LOCKTIME_THRESHOLD) |
+            "j"_mst.If(k < LOCKTIME_THRESHOLD) |
+            "Bzfmxk"_mst;
+        case Fragment::SHA256: return "Bonudmk"_mst;
+        case Fragment::RIPEMD160: return "Bonudmk"_mst;
+        case Fragment::HASH256: return "Bonudmk"_mst;
+        case Fragment::HASH160: return "Bonudmk"_mst;
+        case Fragment::JUST_1: return "Bzufmxk"_mst;
+        case Fragment::JUST_0: return "Bzudemsxk"_mst;
+        case Fragment::WRAP_A: return
+            "W"_mst.If(x << "B"_mst) | // W=B_x
+            (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
+            (x & "udfems"_mst) | // u=u_x, d=d_x, f=f_x, e=e_x, m=m_x, s=s_x
+            "x"_mst; // x
+        case Fragment::WRAP_S: return
+            "W"_mst.If(x << "Bo"_mst) | // W=B_x*o_x
+            (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
+            (x & "udfemsx"_mst); // u=u_x, d=d_x, f=f_x, e=e_x, m=m_x, s=s_x, x=x_x
+        case Fragment::WRAP_C: return
+            "B"_mst.If(x << "K"_mst) | // B=K_x
+            (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
+            (x & "ondfem"_mst) | // o=o_x, n=n_x, d=d_x, f=f_x, e=e_x, m=m_x
+            "us"_mst; // u, s
+        case Fragment::WRAP_D: return
+            "B"_mst.If(x << "Vz"_mst) | // B=V_x*z_x
+            "o"_mst.If(x << "z"_mst) | // o=z_x
+            "e"_mst.If(x << "f"_mst) | // e=f_x
+            (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
+            (x & "ms"_mst) | // m=m_x, s=s_x
+            "nudx"_mst; // n, u, d, x
+        case Fragment::WRAP_V: return
+            "V"_mst.If(x << "B"_mst) | // V=B_x
+            (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
+            (x & "zonms"_mst) | // z=z_x, o=o_x, n=n_x, m=m_x, s=s_x
+            "fx"_mst; // f, x
+        case Fragment::WRAP_J: return
+            "B"_mst.If(x << "Bn"_mst) | // B=B_x*n_x
+            "e"_mst.If(x << "f"_mst) | // e=f_x
+            (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
+            (x & "oums"_mst) | // o=o_x, u=u_x, m=m_x, s=s_x
+            "ndx"_mst; // n, d, x
+        case Fragment::WRAP_N: return
+            (x & "ghijk"_mst) | // g=g_x, h=h_x, i=i_x, j=j_x, k=k_x
+            (x & "Bzondfems"_mst) | // B=B_x, z=z_x, o=o_x, n=n_x, d=d_x, f=f_x, e=e_x, m=m_x, s=s_x
+            "ux"_mst; // u, x
+        case Fragment::AND_V: return
+            (y & "KVB"_mst).If(x << "V"_mst) | // B=V_x*B_y, V=V_x*V_y, K=V_x*K_y
+            (x & "n"_mst) | (y & "n"_mst).If(x << "z"_mst) | // n=n_x+z_x*n_y
+            ((x | y) & "o"_mst).If((x | y) << "z"_mst) | // o=o_x*z_y+z_x*o_y
+            (x & y & "dmz"_mst) | // d=d_x*d_y, m=m_x*m_y, z=z_x*z_y
+            ((x | y) & "s"_mst) | // s=s_x+s_y
+            "f"_mst.If((y << "f"_mst) || (x << "s"_mst)) | // f=f_y+s_x
+            (y & "ux"_mst) | // u=u_y, x=x_y
+            ((x | y) & "ghij"_mst) | // g=g_x+g_y, h=h_x+h_y, i=i_x+i_y, j=j_x+j_y
+            "k"_mst.If(((x & y) << "k"_mst) &&
+                !(((x << "g"_mst) && (y << "h"_mst)) ||
+                ((x << "h"_mst) && (y << "g"_mst)) ||
+                ((x << "i"_mst) && (y << "j"_mst)) ||
+                ((x << "j"_mst) && (y << "i"_mst)))); // k=k_x*k_y*!(g_x*h_y + h_x*g_y + i_x*j_y + j_x*i_y)
+        case Fragment::AND_B: return
+            (x & "B"_mst).If(y << "W"_mst) | // B=B_x*W_y
+            ((x | y) & "o"_mst).If((x | y) << "z"_mst) | // o=o_x*z_y+z_x*o_y
+            (x & "n"_mst) | (y & "n"_mst).If(x << "z"_mst) | // n=n_x+z_x*n_y
+            (x & y & "e"_mst).If((x & y) << "s"_mst) | // e=e_x*e_y*s_x*s_y
+            (x & y & "dzm"_mst) | // d=d_x*d_y, z=z_x*z_y, m=m_x*m_y
+            "f"_mst.If(((x & y) << "f"_mst) || (x << "sf"_mst) || (y << "sf"_mst)) | // f=f_x*f_y + f_x*s_x + f_y*s_y
+            ((x | y) & "s"_mst) | // s=s_x+s_y
+            "ux"_mst | // u, x
+            ((x | y) & "ghij"_mst) | // g=g_x+g_y, h=h_x+h_y, i=i_x+i_y, j=j_x+j_y
+            "k"_mst.If(((x & y) << "k"_mst) &&
+                !(((x << "g"_mst) && (y << "h"_mst)) ||
+                ((x << "h"_mst) && (y << "g"_mst)) ||
+                ((x << "i"_mst) && (y << "j"_mst)) ||
+                ((x << "j"_mst) && (y << "i"_mst)))); // k=k_x*k_y*!(g_x*h_y + h_x*g_y + i_x*j_y + j_x*i_y)
+        case Fragment::OR_B: return
+            "B"_mst.If(x << "Bd"_mst && y << "Wd"_mst) | // B=B_x*d_x*W_x*d_y
+            ((x | y) & "o"_mst).If((x | y) << "z"_mst) | // o=o_x*z_y+z_x*o_y
+            (x & y & "m"_mst).If((x | y) << "s"_mst && (x & y) << "e"_mst) | // m=m_x*m_y*e_x*e_y*(s_x+s_y)
+            (x & y & "zse"_mst) | // z=z_x*z_y, s=s_x*s_y, e=e_x*e_y
+            "dux"_mst | // d, u, x
+            ((x | y) & "ghij"_mst) | // g=g_x+g_y, h=h_x+h_y, i=i_x+i_y, j=j_x+j_y
+            (x & y & "k"_mst); // k=k_x*k_y
+        case Fragment::OR_D: return
+            (y & "B"_mst).If(x << "Bdu"_mst) | // B=B_y*B_x*d_x*u_x
+            (x & "o"_mst).If(y << "z"_mst) | // o=o_x*z_y
+            (x & y & "m"_mst).If(x << "e"_mst && (x | y) << "s"_mst) | // m=m_x*m_y*e_x*(s_x+s_y)
+            (x & y & "zes"_mst) | // z=z_x*z_y, e=e_x*e_y, s=s_x*s_y
+            (y & "ufd"_mst) | // u=u_y, f=f_y, d=d_y
+            "x"_mst | // x
+            ((x | y) & "ghij"_mst) | // g=g_x+g_y, h=h_x+h_y, i=i_x+i_y, j=j_x+j_y
+            (x & y & "k"_mst); // k=k_x*k_y
+        case Fragment::OR_C: return
+            (y & "V"_mst).If(x << "Bdu"_mst) | // V=V_y*B_x*u_x*d_x
+            (x & "o"_mst).If(y << "z"_mst) | // o=o_x*z_y
+            (x & y & "m"_mst).If(x << "e"_mst && (x | y) << "s"_mst) | // m=m_x*m_y*e_x*(s_x+s_y)
+            (x & y & "zs"_mst) | // z=z_x*z_y, s=s_x*s_y
+            "fx"_mst | // f, x
+            ((x | y) & "ghij"_mst) | // g=g_x+g_y, h=h_x+h_y, i=i_x+i_y, j=j_x+j_y
+            (x & y & "k"_mst); // k=k_x*k_y
+        case Fragment::OR_I: return
+            (x & y & "VBKufs"_mst) | // V=V_x*V_y, B=B_x*B_y, K=K_x*K_y, u=u_x*u_y, f=f_x*f_y, s=s_x*s_y
+            "o"_mst.If((x & y) << "z"_mst) | // o=z_x*z_y
+            ((x | y) & "e"_mst).If((x | y) << "f"_mst) | // e=e_x*f_y+f_x*e_y
+            (x & y & "m"_mst).If((x | y) << "s"_mst) | // m=m_x*m_y*(s_x+s_y)
+            ((x | y) & "d"_mst) | // d=d_x+d_y
+            "x"_mst | // x
+            ((x | y) & "ghij"_mst) | // g=g_x+g_y, h=h_x+h_y, i=i_x+i_y, j=j_x+j_y
+            (x & y & "k"_mst); // k=k_x*k_y
+        case Fragment::ANDOR: return
+            (y & z & "BKV"_mst).If(x << "Bdu"_mst) | // B=B_x*d_x*u_x*B_y*B_z, K=B_x*d_x*u_x*K_y*K_z, V=B_x*d_x*u_x*V_y*V_z
+            (x & y & z & "z"_mst) | // z=z_x*z_y*z_z
+            ((x | (y & z)) & "o"_mst).If((x | (y & z)) << "z"_mst) | // o=o_x*z_y*z_z+z_x*o_y*o_z
+            (y & z & "u"_mst) | // u=u_y*u_z
+            (z & "f"_mst).If((x << "s"_mst) || (y << "f"_mst)) | // f=(s_x+f_y)*f_z
+            (z & "d"_mst) | // d=d_z
+            (x & z & "e"_mst).If(x << "s"_mst || y << "f"_mst) | // e=e_x*e_z*(s_x+f_y)
+            (x & y & z & "m"_mst).If(x << "e"_mst && (x | y | z) << "s"_mst) | // m=m_x*m_y*m_z*e_x*(s_x+s_y+s_z)
+            (z & (x | y) & "s"_mst) | // s=s_z*(s_x+s_y)
+            "x"_mst | // x
+            ((x | y | z) & "ghij"_mst) | // g=g_x+g_y+g_z, h=h_x+h_y+h_z, i=i_x+i_y+i_z, j=j_x+j_y_j_z
+            "k"_mst.If(((x & y & z) << "k"_mst) &&
+                !(((x << "g"_mst) && (y << "h"_mst)) ||
+                ((x << "h"_mst) && (y << "g"_mst)) ||
+                ((x << "i"_mst) && (y << "j"_mst)) ||
+                ((x << "j"_mst) && (y << "i"_mst)))); // k=k_x*k_y*k_z* !(g_x*h_y + h_x*g_y + i_x*j_y + j_x*i_y)
+        case Fragment::MULTI: return "Bnudemsk"_mst;
+        case Fragment::THRESH: {
+            bool all_e = true;
+            bool all_m = true;
+            uint32_t args = 0;
+            uint32_t num_s = 0;
+            Type acc_tl = "k"_mst;
+            for (size_t i = 0; i < sub_types.size(); ++i) {
+                Type t = sub_types[i];
+                if (!(t << (i ? "Wdu"_mst : "Bdu"_mst))) return ""_mst; // Require Bdu, Wdu, Wdu, ...
+                if (!(t << "e"_mst)) all_e = false;
+                if (!(t << "m"_mst)) all_m = false;
+                if (t << "s"_mst) num_s += 1;
+                args += (t << "z"_mst) ? 0 : (t << "o"_mst) ? 1 : 2;
+                acc_tl = ((acc_tl | t) & "ghij"_mst) |
+                    // Thresh contains a combination of timelocks if it has threshold > 1 and
+                    // it contains two different children that have different types of timelocks
+                    // Note how if any of the children don't have "k", the parent also does not have "k"
+                    "k"_mst.If(((acc_tl & t) << "k"_mst) && ((k <= 1) ||
+                        ((k > 1) && !(((acc_tl << "g"_mst) && (t << "h"_mst)) ||
+                        ((acc_tl << "h"_mst) && (t << "g"_mst)) ||
+                        ((acc_tl << "i"_mst) && (t << "j"_mst)) ||
+                        ((acc_tl << "j"_mst) && (t << "i"_mst))))));
+            }
+            return "Bdu"_mst |
+                   "z"_mst.If(args == 0) | // z=all z
+                   "o"_mst.If(args == 1) | // o=all z except one o
+                   "e"_mst.If(all_e && num_s == n_subs) | // e=all e and all s
+                   "m"_mst.If(all_e && all_m && num_s >= n_subs - k) | // m=all e, >=(n-k) s
+                   "s"_mst.If(num_s >= n_subs - k + 1) |  // s= >=(n-k+1) s
+                   acc_tl; // timelock info
+            }
+    }
+    assert(false);
+    return ""_mst;
+}
+
+size_t ComputeScriptLen(Fragment nodetype, Type sub0typ, size_t subsize, uint32_t k, size_t n_subs, size_t n_keys) {
+    switch (nodetype) {
+        case Fragment::JUST_1:
+        case Fragment::JUST_0: return 1;
+        case Fragment::PK_K: return 34;
+        case Fragment::PK_H: return 3 + 21;
+        case Fragment::OLDER:
+        case Fragment::AFTER: return 1 + BuildScript(k).size();
+        case Fragment::HASH256:
+        case Fragment::SHA256: return 4 + 2 + 33;
+        case Fragment::HASH160:
+        case Fragment::RIPEMD160: return 4 + 2 + 21;
+        case Fragment::MULTI: return 3 + (n_keys > 16) + (k > 16) + 34 * n_keys;
+        case Fragment::AND_V: return subsize;
+        case Fragment::WRAP_V: return subsize + (sub0typ << "x"_mst);
+        case Fragment::WRAP_S:
+        case Fragment::WRAP_C:
+        case Fragment::WRAP_N:
+        case Fragment::AND_B:
+        case Fragment::OR_B: return subsize + 1;
+        case Fragment::WRAP_A:
+        case Fragment::OR_C: return subsize + 2;
+        case Fragment::WRAP_D:
+        case Fragment::OR_D:
+        case Fragment::OR_I:
+        case Fragment::ANDOR: return subsize + 3;
+        case Fragment::WRAP_J: return subsize + 4;
+        case Fragment::THRESH: return subsize + n_subs + BuildScript(k).size();
+    }
+    assert(false);
+    return 0;
+}
+
+int FindNextChar(Span<const char> sp, const char m)
+{
+    for (int i = 0; i < (int)sp.size(); ++i) {
+        if (sp[i] == m) return i;
+        // We only search within the current parentheses
+        if (sp[i] == ')') break;
+    }
+    return -1;
+}
+
+} // namespace internal
+} // namespace miniscript
diff --git a/src/script/miniscript.h b/src/script/miniscript.h
new file mode 100644
index 0000000000..a394aed146
--- /dev/null
+++ b/src/script/miniscript.h
@@ -0,0 +1,1020 @@
+// Copyright (c) 2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_SCRIPT_MINISCRIPT_H
+#define BITCOIN_SCRIPT_MINISCRIPT_H
+
+#include <algorithm>
+#include <numeric>
+#include <memory>
+#include <optional>
+#include <string>
+#include <vector>
+
+#include <stdlib.h>
+#include <assert.h>
+
+#include <policy/policy.h>
+#include <primitives/transaction.h>
+#include <script/script.h>
+#include <span.h>
+#include <util/spanparsing.h>
+#include <util/strencodings.h>
+#include <util/string.h>
+#include <util/vector.h>
+
+namespace miniscript {
+
+/** This type encapsulates the miniscript type system properties.
+ *
+ * Every miniscript expression is one of 4 basic types, and additionally has
+ * a number of boolean type properties.
+ *
+ * The basic types are:
+ * - "B" Base:
+ *   - Takes its inputs from the top of the stack.
+ *   - When satisfied, pushes a nonzero value of up to 4 bytes onto the stack.
+ *   - When dissatisfied, pushes a 0 onto the stack.
+ *   - This is used for most expressions, and required for the top level one.
+ *   - For example: older(n) = <n> OP_CHECKSEQUENCEVERIFY.
+ * - "V" Verify:
+ *   - Takes its inputs from the top of the stack.
+ *   - When satisfactied, pushes nothing.
+ *   - Cannot be dissatisfied.
+ *   - This can be obtained by adding an OP_VERIFY to a B, modifying the last opcode
+ *     of a B to its -VERIFY version (only for OP_CHECKSIG, OP_CHECKSIGVERIFY
+ *     and OP_EQUAL), or by combining a V fragment under some conditions.
+ *   - For example vc:pk_k(key) = <key> OP_CHECKSIGVERIFY
+ * - "K" Key:
+ *   - Takes its inputs from the top of the stack.
+ *   - Becomes a B when followed by OP_CHECKSIG.
+ *   - Always pushes a public key onto the stack, for which a signature is to be
+ *     provided to satisfy the expression.
+ *   - For example pk_h(key) = OP_DUP OP_HASH160 <Hash160(key)> OP_EQUALVERIFY
+ * - "W" Wrapped:
+ *   - Takes its input from one below the top of the stack.
+ *   - When satisfied, pushes a nonzero value (like B) on top of the stack, or one below.
+ *   - When dissatisfied, pushes 0 op top of the stack or one below.
+ *   - Is always "OP_SWAP [B]" or "OP_TOALTSTACK [B] OP_FROMALTSTACK".
+ *   - For example sc:pk_k(key) = OP_SWAP <key> OP_CHECKSIG
+ *
+ * There a type properties that help reasoning about correctness:
+ * - "z" Zero-arg:
+ *   - Is known to always consume exactly 0 stack elements.
+ *   - For example after(n) = <n> OP_CHECKLOCKTIMEVERIFY
+ * - "o" One-arg:
+ *   - Is known to always consume exactly 1 stack element.
+ *   - Conflicts with property 'z'
+ *   - For example sha256(hash) = OP_SIZE 32 OP_EQUALVERIFY OP_SHA256 <hash> OP_EQUAL
+ * - "n" Nonzero:
+ *   - For every way this expression can be satisfied, a satisfaction exists that never needs
+ *     a zero top stack element.
+ *   - Conflicts with property 'z' and with type 'W'.
+ * - "d" Dissatisfiable:
+ *   - There is an easy way to construct a dissatisfaction for this expression.
+ *   - Conflicts with type 'V'.
+ * - "u" Unit:
+ *   - In case of satisfaction, an exact 1 is put on the stack (rather than just nonzero).
+ *   - Conflicts with type 'V'.
+ *
+ * Additional type properties help reasoning about nonmalleability:
+ * - "e" Expression:
+ *   - This implies property 'd', but the dissatisfaction is nonmalleable.
+ *   - This generally requires 'e' for all subexpressions which are invoked for that
+ *     dissatifsaction, and property 'f' for the unexecuted subexpressions in that case.
+ *   - Conflicts with type 'V'.
+ * - "f" Forced:
+ *   - Dissatisfactions (if any) for this expression always involve at least one signature.
+ *   - Is always true for type 'V'.
+ * - "s" Safe:
+ *   - Satisfactions for this expression always involve at least one signature.
+ * - "m" Nonmalleable:
+ *   - For every way this expression can be satisfied (which may be none),
+ *     a nonmalleable satisfaction exists.
+ *   - This generally requires 'm' for all subexpressions, and 'e' for all subexpressions
+ *     which are dissatisfied when satisfying the parent.
+ *
+ * One type property is an implementation detail:
+ * - "x" Expensive verify:
+ *   - Expressions with this property have a script whose last opcode is not EQUAL, CHECKSIG, or CHECKMULTISIG.
+ *   - Not having this property means that it can be converted to a V at no cost (by switching to the
+ *     -VERIFY version of the last opcode).
+ *
+ * Five more type properties for representing timelock information. Spend paths
+ * in miniscripts containing conflicting timelocks and heightlocks cannot be spent together.
+ * This helps users detect if miniscript does not match the semantic behaviour the
+ * user expects.
+ * - "g" Whether the branch contains a relative time timelock
+ * - "h" Whether the branch contains a relative height timelock
+ * - "i" Whether the branch contains an absolute time timelock
+ * - "j" Whether the branch contains an absolute height timelock
+ * - "k"
+ *   - Whether all satisfactions of this expression don't contain a mix of heightlock and timelock
+ *     of the same type.
+ *   - If the miniscript does not have the "k" property, the miniscript template will not match
+ *     the user expectation of the corresponding spending policy.
+ * For each of these properties the subset rule holds: an expression with properties X, Y, and Z, is also
+ * valid in places where an X, a Y, a Z, an XY, ... is expected.
+*/
+class Type {
+    //! Internal bitmap of properties (see ""_mst operator for details).
+    uint32_t m_flags;
+
+    //! Internal constructor used by the ""_mst operator.
+    explicit constexpr Type(uint32_t flags) : m_flags(flags) {}
+
+public:
+    //! The only way to publicly construct a Type is using this literal operator.
+    friend constexpr Type operator"" _mst(const char* c, size_t l);
+
+    //! Compute the type with the union of properties.
+    constexpr Type operator|(Type x) const { return Type(m_flags | x.m_flags); }
+
+    //! Compute the type with the intersection of properties.
+    constexpr Type operator&(Type x) const { return Type(m_flags & x.m_flags); }
+
+    //! Check whether the left hand's properties are superset of the right's (= left is a subtype of right).
+    constexpr bool operator<<(Type x) const { return (x.m_flags & ~m_flags) == 0; }
+
+    //! Comparison operator to enable use in sets/maps (total ordering incompatible with <<).
+    constexpr bool operator<(Type x) const { return m_flags < x.m_flags; }
+
+    //! Equality operator.
+    constexpr bool operator==(Type x) const { return m_flags == x.m_flags; }
+
+    //! The empty type if x is false, itself otherwise.
+    constexpr Type If(bool x) const { return Type(x ? m_flags : 0); }
+};
+
+//! Literal operator to construct Type objects.
+inline constexpr Type operator"" _mst(const char* c, size_t l) {
+    Type typ{0};
+
+    for (const char *p = c; p < c + l; p++) {
+        typ = typ | Type(
+            *p == 'B' ? 1 << 0 : // Base type
+            *p == 'V' ? 1 << 1 : // Verify type
+            *p == 'K' ? 1 << 2 : // Key type
+            *p == 'W' ? 1 << 3 : // Wrapped type
+            *p == 'z' ? 1 << 4 : // Zero-arg property
+            *p == 'o' ? 1 << 5 : // One-arg property
+            *p == 'n' ? 1 << 6 : // Nonzero arg property
+            *p == 'd' ? 1 << 7 : // Dissatisfiable property
+            *p == 'u' ? 1 << 8 : // Unit property
+            *p == 'e' ? 1 << 9 : // Expression property
+            *p == 'f' ? 1 << 10 : // Forced property
+            *p == 's' ? 1 << 11 : // Safe property
+            *p == 'm' ? 1 << 12 : // Nonmalleable property
+            *p == 'x' ? 1 << 13 : // Expensive verify
+            *p == 'g' ? 1 << 14 : // older: contains relative time timelock   (csv_time)
+            *p == 'h' ? 1 << 15 : // older: contains relative height timelock (csv_height)
+            *p == 'i' ? 1 << 16 : // after: contains time timelock   (cltv_time)
+            *p == 'j' ? 1 << 17 : // after: contains height timelock   (cltv_height)
+            *p == 'k' ? 1 << 18 : // does not contain a combination of height and time locks
+            (throw std::logic_error("Unknown character in _mst literal"), 0)
+        );
+    }
+
+    return typ;
+}
+
+template<typename Key> struct Node;
+template<typename Key> using NodeRef = std::shared_ptr<const Node<Key>>;
+
+//! Construct a miniscript node as a shared_ptr.
+template<typename Key, typename... Args>
+NodeRef<Key> MakeNodeRef(Args&&... args) { return std::make_shared<const Node<Key>>(std::forward<Args>(args)...); }
+
+//! The different node types in miniscript.
+enum class Fragment {
+    JUST_0,    //!< OP_0
+    JUST_1,    //!< OP_1
+    PK_K,      //!< [key]
+    PK_H,      //!< OP_DUP OP_HASH160 [keyhash] OP_EQUALVERIFY
+    OLDER,     //!< [n] OP_CHECKSEQUENCEVERIFY
+    AFTER,     //!< [n] OP_CHECKLOCKTIMEVERIFY
+    SHA256,    //!< OP_SIZE 32 OP_EQUALVERIFY OP_SHA256 [hash] OP_EQUAL
+    HASH256,   //!< OP_SIZE 32 OP_EQUALVERIFY OP_HASH256 [hash] OP_EQUAL
+    RIPEMD160, //!< OP_SIZE 32 OP_EQUALVERIFY OP_RIPEMD160 [hash] OP_EQUAL
+    HASH160,   //!< OP_SIZE 32 OP_EQUALVERIFY OP_HASH160 [hash] OP_EQUAL
+    WRAP_A,    //!< OP_TOALTSTACK [X] OP_FROMALTSTACK
+    WRAP_S,    //!< OP_SWAP [X]
+    WRAP_C,    //!< [X] OP_CHECKSIG
+    WRAP_D,    //!< OP_DUP OP_IF [X] OP_ENDIF
+    WRAP_V,    //!< [X] OP_VERIFY (or -VERIFY version of last opcode in X)
+    WRAP_J,    //!< OP_SIZE OP_0NOTEQUAL OP_IF [X] OP_ENDIF
+    WRAP_N,    //!< [X] OP_0NOTEQUAL
+    AND_V,     //!< [X] [Y]
+    AND_B,     //!< [X] [Y] OP_BOOLAND
+    OR_B,      //!< [X] [Y] OP_BOOLOR
+    OR_C,      //!< [X] OP_NOTIF [Y] OP_ENDIF
+    OR_D,      //!< [X] OP_IFDUP OP_NOTIF [Y] OP_ENDIF
+    OR_I,      //!< OP_IF [X] OP_ELSE [Y] OP_ENDIF
+    ANDOR,     //!< [X] OP_NOTIF [Z] OP_ELSE [Y] OP_ENDIF
+    THRESH,    //!< [X1] ([Xn] OP_ADD)* [k] OP_EQUAL
+    MULTI,     //!< [k] [key_n]* [n] OP_CHECKMULTISIG
+    // AND_N(X,Y) is represented as ANDOR(X,Y,0)
+    // WRAP_T(X) is represented as AND_V(X,1)
+    // WRAP_L(X) is represented as OR_I(0,X)
+    // WRAP_U(X) is represented as OR_I(X,0)
+};
+
+namespace internal {
+
+//! Helper function for Node::CalcType.
+Type ComputeType(Fragment nodetype, Type x, Type y, Type z, const std::vector<Type>& sub_types, uint32_t k, size_t data_size, size_t n_subs, size_t n_keys);
+
+//! Helper function for Node::CalcScriptLen.
+size_t ComputeScriptLen(Fragment nodetype, Type sub0typ, size_t subsize, uint32_t k, size_t n_subs, size_t n_keys);
+
+//! A helper sanitizer/checker for the output of CalcType.
+Type SanitizeType(Type x);
+
+} // namespace internal
+
+//! A node in a miniscript expression.
+template<typename Key>
+struct Node {
+    //! What node type this node is.
+    const Fragment nodetype;
+    //! The k parameter (time for OLDER/AFTER, threshold for THRESH(_M))
+    const uint32_t k = 0;
+    //! The keys used by this expression (only for PK_K/PK_H/MULTI)
+    const std::vector<Key> keys;
+    //! The data bytes in this expression (only for HASH160/HASH256/SHA256/RIPEMD10).
+    const std::vector<unsigned char> data;
+    //! Subexpressions (for WRAP_*/AND_*/OR_*/ANDOR/THRESH)
+    const std::vector<NodeRef<Key>> subs;
+
+private:
+    //! Cached expression type (computed by CalcType and fed through SanitizeType).
+    const Type typ;
+    //! Cached script length (computed by CalcScriptLen).
+    const size_t scriptlen;
+
+    //! Compute the length of the script for this miniscript (including children).
+    size_t CalcScriptLen() const {
+        size_t subsize = 0;
+        for (const auto& sub : subs) {
+            subsize += sub->ScriptSize();
+        }
+        Type sub0type = subs.size() > 0 ? subs[0]->GetType() : ""_mst;
+        return internal::ComputeScriptLen(nodetype, sub0type, subsize, k, subs.size(), keys.size());
+    }
+
+    /* Apply a recursive algorithm to a Miniscript tree, without actual recursive calls.
+     *
+     * The algorithm is defined by two functions: downfn and upfn. Conceptually, the
+     * result can be thought of as first using downfn to compute a "state" for each node,
+     * from the root down to the leaves. Then upfn is used to compute a "result" for each
+     * node, from the leaves back up to the root, which is then returned. In the actual
+     * implementation, both functions are invoked in an interleaved fashion, performing a
+     * depth-first traversal of the tree.
+     *
+     * In more detail, it is invoked as node.TreeEvalMaybe<Result>(root, downfn, upfn):
+     * - root is the state of the root node, of type State.
+     * - downfn is a callable (State&, const Node&, size_t) -> State, which given a
+     *   node, its state, and an index of one of its children, computes the state of that
+     *   child. It can modify the state. Children of a given node will have downfn()
+     *   called in order.
+     * - upfn is a callable (State&&, const Node&, Span<Result>) -> std::optional<Result>,
+     *   which given a node, its state, and a Span of the results of its children,
+     *   computes the result of the node. If std::nullopt is returned by upfn,
+     *   TreeEvalMaybe() immediately returns std::nullopt.
+     * The return value of TreeEvalMaybe is the result of the root node.
+     */
+    template<typename Result, typename State, typename DownFn, typename UpFn>
+    std::optional<Result> TreeEvalMaybe(State root_state, DownFn downfn, UpFn upfn) const
+    {
+        /** Entries of the explicit stack tracked in this algorithm. */
+        struct StackElem
+        {
+            const Node& node; //!< The node being evaluated.
+            size_t expanded; //!< How many children of this node have been expanded.
+            State state; //!< The state for that node.
+
+            StackElem(const Node& node_, size_t exp_, State&& state_) :
+                node(node_), expanded(exp_), state(std::move(state_)) {}
+        };
+        /* Stack of tree nodes being explored. */
+        std::vector<StackElem> stack;
+        /* Results of subtrees so far. Their order and mapping to tree nodes
+         * is implicitly defined by stack. */
+        std::vector<Result> results;
+        stack.emplace_back(*this, 0, std::move(root_state));
+
+        /* Here is a demonstration of the algorithm, for an example tree A(B,C(D,E),F).
+         * State variables are omitted for simplicity.
+         *
+         * First: stack=[(A,0)] results=[]
+         *        stack=[(A,1),(B,0)] results=[]
+         *        stack=[(A,1)] results=[B]
+         *        stack=[(A,2),(C,0)] results=[B]
+         *        stack=[(A,2),(C,1),(D,0)] results=[B]
+         *        stack=[(A,2),(C,1)] results=[B,D]
+         *        stack=[(A,2),(C,2),(E,0)] results=[B,D]
+         *        stack=[(A,2),(C,2)] results=[B,D,E]
+         *        stack=[(A,2)] results=[B,C]
+         *        stack=[(A,3),(F,0)] results=[B,C]
+         *        stack=[(A,3)] results=[B,C,F]
+         * Final: stack=[] results=[A]
+         */
+        while (stack.size()) {
+            const Node& node = stack.back().node;
+            if (stack.back().expanded < node.subs.size()) {
+                /* We encounter a tree node with at least one unexpanded child.
+                 * Expand it. By the time we hit this node again, the result of
+                 * that child (and all earlier children) will be at the end of `results`. */
+                size_t child_index = stack.back().expanded++;
+                State child_state = downfn(stack.back().state, node, child_index);
+                stack.emplace_back(*node.subs[child_index], 0, std::move(child_state));
+                continue;
+            }
+            // Invoke upfn with the last node.subs.size() elements of results as input.
+            assert(results.size() >= node.subs.size());
+            std::optional<Result> result{upfn(std::move(stack.back().state), node,
+                Span<Result>{results}.last(node.subs.size()))};
+            // If evaluation returns std::nullopt, abort immediately.
+            if (!result) return {};
+            // Replace the last node.subs.size() elements of results with the new result.
+            results.erase(results.end() - node.subs.size(), results.end());
+            results.push_back(std::move(*result));
+            stack.pop_back();
+        }
+        // The final remaining results element is the root result, return it.
+        assert(results.size() == 1);
+        return std::move(results[0]);
+    }
+
+    /** Like TreeEvalMaybe, but always produces a result. upfn must return Result. */
+    template<typename Result, typename State, typename DownFn, typename UpFn>
+    Result TreeEval(State root_state, DownFn&& downfn, UpFn upfn) const
+    {
+        // Invoke TreeEvalMaybe with upfn wrapped to return std::optional<Result>, and then
+        // unconditionally dereference the result (it cannot be std::nullopt).
+        return std::move(*TreeEvalMaybe<Result>(std::move(root_state),
+            std::forward<DownFn>(downfn),
+            [&upfn](State&& state, const Node& node, Span<Result> subs) {
+                Result res{upfn(std::move(state), node, subs)};
+                return std::optional<Result>(std::move(res));
+            }
+        ));
+    }
+
+    //! Compute the type for this miniscript.
+    Type CalcType() const {
+        using namespace internal;
+
+        // THRESH has a variable number of subexpressions
+        std::vector<Type> sub_types;
+        if (nodetype == Fragment::THRESH) {
+            for (const auto& sub : subs) sub_types.push_back(sub->GetType());
+        }
+        // All other nodes than THRESH can be computed just from the types of the 0-3 subexpressions.
+        Type x = subs.size() > 0 ? subs[0]->GetType() : ""_mst;
+        Type y = subs.size() > 1 ? subs[1]->GetType() : ""_mst;
+        Type z = subs.size() > 2 ? subs[2]->GetType() : ""_mst;
+
+        return SanitizeType(ComputeType(nodetype, x, y, z, sub_types, k, data.size(), subs.size(), keys.size()));
+    }
+
+public:
+    template<typename Ctx>
+    CScript ToScript(const Ctx& ctx) const
+    {
+        // To construct the CScript for a Miniscript object, we use the TreeEval algorithm.
+        // The State is a boolean: whether or not the node's script expansion is followed
+        // by an OP_VERIFY (which may need to be combined with the last script opcode).
+        auto downfn = [](bool verify, const Node& node, size_t index) {
+            // For WRAP_V, the subexpression is certainly followed by OP_VERIFY.
+            if (node.nodetype == Fragment::WRAP_V) return true;
+            // The subexpression of WRAP_S, and the last subexpression of AND_V
+            // inherit the followed-by-OP_VERIFY property from the parent.
+            if (node.nodetype == Fragment::WRAP_S ||
+                (node.nodetype == Fragment::AND_V && index == 1)) return verify;
+            return false;
+        };
+        // The upward function computes for a node, given its followed-by-OP_VERIFY status
+        // and the CScripts of its child nodes, the CScript of the node.
+        auto upfn = [&ctx](bool verify, const Node& node, Span<CScript> subs) -> CScript {
+            switch (node.nodetype) {
+                case Fragment::PK_K: return BuildScript(ctx.ToPKBytes(node.keys[0]));
+                case Fragment::PK_H: return BuildScript(OP_DUP, OP_HASH160, ctx.ToPKHBytes(node.keys[0]), OP_EQUALVERIFY);
+                case Fragment::OLDER: return BuildScript(node.k, OP_CHECKSEQUENCEVERIFY);
+                case Fragment::AFTER: return BuildScript(node.k, OP_CHECKLOCKTIMEVERIFY);
+                case Fragment::SHA256: return BuildScript(OP_SIZE, 32, OP_EQUALVERIFY, OP_SHA256, node.data, verify ? OP_EQUALVERIFY : OP_EQUAL);
+                case Fragment::RIPEMD160: return BuildScript(OP_SIZE, 32, OP_EQUALVERIFY, OP_RIPEMD160, node.data, verify ? OP_EQUALVERIFY : OP_EQUAL);
+                case Fragment::HASH256: return BuildScript(OP_SIZE, 32, OP_EQUALVERIFY, OP_HASH256, node.data, verify ? OP_EQUALVERIFY : OP_EQUAL);
+                case Fragment::HASH160: return BuildScript(OP_SIZE, 32, OP_EQUALVERIFY, OP_HASH160, node.data, verify ? OP_EQUALVERIFY : OP_EQUAL);
+                case Fragment::WRAP_A: return BuildScript(OP_TOALTSTACK, subs[0], OP_FROMALTSTACK);
+                case Fragment::WRAP_S: return BuildScript(OP_SWAP, subs[0]);
+                case Fragment::WRAP_C: return BuildScript(std::move(subs[0]), verify ? OP_CHECKSIGVERIFY : OP_CHECKSIG);
+                case Fragment::WRAP_D: return BuildScript(OP_DUP, OP_IF, subs[0], OP_ENDIF);
+                case Fragment::WRAP_V: {
+                    if (node.subs[0]->GetType() << "x"_mst) {
+                        return BuildScript(std::move(subs[0]), OP_VERIFY);
+                    } else {
+                        return std::move(subs[0]);
+                    }
+                }
+                case Fragment::WRAP_J: return BuildScript(OP_SIZE, OP_0NOTEQUAL, OP_IF, subs[0], OP_ENDIF);
+                case Fragment::WRAP_N: return BuildScript(std::move(subs[0]), OP_0NOTEQUAL);
+                case Fragment::JUST_1: return BuildScript(OP_1);
+                case Fragment::JUST_0: return BuildScript(OP_0);
+                case Fragment::AND_V: return BuildScript(std::move(subs[0]), subs[1]);
+                case Fragment::AND_B: return BuildScript(std::move(subs[0]), subs[1], OP_BOOLAND);
+                case Fragment::OR_B: return BuildScript(std::move(subs[0]), subs[1], OP_BOOLOR);
+                case Fragment::OR_D: return BuildScript(std::move(subs[0]), OP_IFDUP, OP_NOTIF, subs[1], OP_ENDIF);
+                case Fragment::OR_C: return BuildScript(std::move(subs[0]), OP_NOTIF, subs[1], OP_ENDIF);
+                case Fragment::OR_I: return BuildScript(OP_IF, subs[0], OP_ELSE, subs[1], OP_ENDIF);
+                case Fragment::ANDOR: return BuildScript(std::move(subs[0]), OP_NOTIF, subs[2], OP_ELSE, subs[1], OP_ENDIF);
+                case Fragment::MULTI: {
+                    CScript script = BuildScript(node.k);
+                    for (const auto& key : node.keys) {
+                        script = BuildScript(std::move(script), ctx.ToPKBytes(key));
+                    }
+                    return BuildScript(std::move(script), node.keys.size(), verify ? OP_CHECKMULTISIGVERIFY : OP_CHECKMULTISIG);
+                }
+                case Fragment::THRESH: {
+                    CScript script = std::move(subs[0]);
+                    for (size_t i = 1; i < subs.size(); ++i) {
+                        script = BuildScript(std::move(script), subs[i], OP_ADD);
+                    }
+                    return BuildScript(std::move(script), node.k, verify ? OP_EQUALVERIFY : OP_EQUAL);
+                }
+            }
+            assert(false);
+            return {};
+        };
+        return TreeEval<CScript>(false, downfn, upfn);
+    }
+
+    template<typename CTx>
+    bool ToString(const CTx& ctx, std::string& ret) const {
+        // To construct the std::string representation for a Miniscript object, we use
+        // the TreeEvalMaybe algorithm. The State is a boolean: whether the parent node is a
+        // wrapper. If so, non-wrapper expressions must be prefixed with a ":".
+        auto downfn = [](bool, const Node& node, size_t) {
+            return (node.nodetype == Fragment::WRAP_A || node.nodetype == Fragment::WRAP_S ||
+                    node.nodetype == Fragment::WRAP_D || node.nodetype == Fragment::WRAP_V ||
+                    node.nodetype == Fragment::WRAP_J || node.nodetype == Fragment::WRAP_N ||
+                    node.nodetype == Fragment::WRAP_C ||
+                    (node.nodetype == Fragment::AND_V && node.subs[1]->nodetype == Fragment::JUST_1) ||
+                    (node.nodetype == Fragment::OR_I && node.subs[0]->nodetype == Fragment::JUST_0) ||
+                    (node.nodetype == Fragment::OR_I && node.subs[1]->nodetype == Fragment::JUST_0));
+        };
+        // The upward function computes for a node, given whether its parent is a wrapper,
+        // and the string representations of its child nodes, the string representation of the node.
+        auto upfn = [&ctx](bool wrapped, const Node& node, Span<std::string> subs) -> std::optional<std::string> {
+            std::string ret = wrapped ? ":" : "";
+
+            switch (node.nodetype) {
+                case Fragment::WRAP_A: return "a" + std::move(subs[0]);
+                case Fragment::WRAP_S: return "s" + std::move(subs[0]);
+                case Fragment::WRAP_C:
+                    if (node.subs[0]->nodetype == Fragment::PK_K) {
+                        // pk(K) is syntactic sugar for c:pk_k(K)
+                        std::string key_str;
+                        if (!ctx.ToString(node.subs[0]->keys[0], key_str)) return {};
+                        return std::move(ret) + "pk(" + std::move(key_str) + ")";
+                    }
+                    if (node.subs[0]->nodetype == Fragment::PK_H) {
+                        // pkh(K) is syntactic sugar for c:pk_h(K)
+                        std::string key_str;
+                        if (!ctx.ToString(node.subs[0]->keys[0], key_str)) return {};
+                        return std::move(ret) + "pkh(" + std::move(key_str) + ")";
+                    }
+                    return "c" + std::move(subs[0]);
+                case Fragment::WRAP_D: return "d" + std::move(subs[0]);
+                case Fragment::WRAP_V: return "v" + std::move(subs[0]);
+                case Fragment::WRAP_J: return "j" + std::move(subs[0]);
+                case Fragment::WRAP_N: return "n" + std::move(subs[0]);
+                case Fragment::AND_V:
+                    // t:X is syntactic sugar for and_v(X,1).
+                    if (node.subs[1]->nodetype == Fragment::JUST_1) return "t" + std::move(subs[0]);
+                    break;
+                case Fragment::OR_I:
+                    if (node.subs[0]->nodetype == Fragment::JUST_0) return "l" + std::move(subs[1]);
+                    if (node.subs[1]->nodetype == Fragment::JUST_0) return "u" + std::move(subs[0]);
+                    break;
+                default: break;
+            }
+            switch (node.nodetype) {
+                case Fragment::PK_K: {
+                    std::string key_str;
+                    if (!ctx.ToString(node.keys[0], key_str)) return {};
+                    return std::move(ret) + "pk_k(" + std::move(key_str) + ")";
+                }
+                case Fragment::PK_H: {
+                    std::string key_str;
+                    if (!ctx.ToString(node.keys[0], key_str)) return {};
+                    return std::move(ret) + "pk_h(" + std::move(key_str) + ")";
+                }
+                case Fragment::AFTER: return std::move(ret) + "after(" + ::ToString(node.k) + ")";
+                case Fragment::OLDER: return std::move(ret) + "older(" + ::ToString(node.k) + ")";
+                case Fragment::HASH256: return std::move(ret) + "hash256(" + HexStr(node.data) + ")";
+                case Fragment::HASH160: return std::move(ret) + "hash160(" + HexStr(node.data) + ")";
+                case Fragment::SHA256: return std::move(ret) + "sha256(" + HexStr(node.data) + ")";
+                case Fragment::RIPEMD160: return std::move(ret) + "ripemd160(" + HexStr(node.data) + ")";
+                case Fragment::JUST_1: return std::move(ret) + "1";
+                case Fragment::JUST_0: return std::move(ret) + "0";
+                case Fragment::AND_V: return std::move(ret) + "and_v(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
+                case Fragment::AND_B: return std::move(ret) + "and_b(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
+                case Fragment::OR_B: return std::move(ret) + "or_b(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
+                case Fragment::OR_D: return std::move(ret) + "or_d(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
+                case Fragment::OR_C: return std::move(ret) + "or_c(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
+                case Fragment::OR_I: return std::move(ret) + "or_i(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
+                case Fragment::ANDOR:
+                    // and_n(X,Y) is syntactic sugar for andor(X,Y,0).
+                    if (node.subs[2]->nodetype == Fragment::JUST_0) return std::move(ret) + "and_n(" + std::move(subs[0]) + "," + std::move(subs[1]) + ")";
+                    return std::move(ret) + "andor(" + std::move(subs[0]) + "," + std::move(subs[1]) + "," + std::move(subs[2]) + ")";
+                case Fragment::MULTI: {
+                    auto str = std::move(ret) + "multi(" + ::ToString(node.k);
+                    for (const auto& key : node.keys) {
+                        std::string key_str;
+                        if (!ctx.ToString(key, key_str)) return {};
+                        str += "," + std::move(key_str);
+                    }
+                    return std::move(str) + ")";
+                }
+                case Fragment::THRESH: {
+                    auto str = std::move(ret) + "thresh(" + ::ToString(node.k);
+                    for (auto& sub : subs) {
+                        str += "," + std::move(sub);
+                    }
+                    return std::move(str) + ")";
+                }
+                default: assert(false);
+            }
+            return ""; // Should never be reached.
+        };
+
+        auto res = TreeEvalMaybe<std::string>(false, downfn, upfn);
+        if (res.has_value()) ret = std::move(*res);
+        return res.has_value();
+    }
+
+public:
+    //! Return the size of the script for this expression (faster than ToScript().size()).
+    size_t ScriptSize() const { return scriptlen; }
+
+    //! Return the expression type.
+    Type GetType() const { return typ; }
+
+    //! Check whether this node is valid at all.
+    bool IsValid() const { return !(GetType() == ""_mst) && ScriptSize() <= MAX_STANDARD_P2WSH_SCRIPT_SIZE; }
+
+    //! Check whether this node is valid as a script on its own.
+    bool IsValidTopLevel() const { return IsValid() && GetType() << "B"_mst; }
+
+    //! Check whether this script can always be satisfied in a non-malleable way.
+    bool IsNonMalleable() const { return GetType() << "m"_mst; }
+
+    //! Check whether this script always needs a signature.
+    bool NeedsSignature() const { return GetType() << "s"_mst; }
+
+    //! Do all sanity checks.
+    bool IsSane() const { return IsValid() && GetType() << "mk"_mst; }
+
+    //! Check whether this node is safe as a script on its own.
+    bool IsSaneTopLevel() const { return IsValidTopLevel() && IsSane() && NeedsSignature(); }
+
+    //! Equality testing.
+    bool operator==(const Node<Key>& arg) const
+    {
+        if (nodetype != arg.nodetype) return false;
+        if (k != arg.k) return false;
+        if (data != arg.data) return false;
+        if (keys != arg.keys) return false;
+        if (subs.size() != arg.subs.size()) return false;
+        for (size_t i = 0; i < subs.size(); ++i) {
+            if (!(*subs[i] == *arg.subs[i])) return false;
+        }
+        assert(scriptlen == arg.scriptlen);
+        assert(typ == arg.typ);
+        return true;
+    }
+
+    // Constructors with various argument combinations.
+    Node(Fragment nt, std::vector<NodeRef<Key>> sub, std::vector<unsigned char> arg, uint32_t val = 0) : nodetype(nt), k(val), data(std::move(arg)), subs(std::move(sub)), typ(CalcType()), scriptlen(CalcScriptLen()) {}
+    Node(Fragment nt, std::vector<unsigned char> arg, uint32_t val = 0) : nodetype(nt), k(val), data(std::move(arg)), typ(CalcType()), scriptlen(CalcScriptLen()) {}
+    Node(Fragment nt, std::vector<NodeRef<Key>> sub, std::vector<Key> key, uint32_t val = 0) : nodetype(nt), k(val), keys(std::move(key)), subs(std::move(sub)), typ(CalcType()), scriptlen(CalcScriptLen()) {}
+    Node(Fragment nt, std::vector<Key> key, uint32_t val = 0) : nodetype(nt), k(val), keys(std::move(key)), typ(CalcType()), scriptlen(CalcScriptLen()) {}
+    Node(Fragment nt, std::vector<NodeRef<Key>> sub, uint32_t val = 0) : nodetype(nt), k(val), subs(std::move(sub)), typ(CalcType()), scriptlen(CalcScriptLen()) {}
+    Node(Fragment nt, uint32_t val = 0) : nodetype(nt), k(val), typ(CalcType()), scriptlen(CalcScriptLen()) {}
+};
+
+namespace internal {
+
+enum class ParseContext {
+    /** An expression which may be begin with wrappers followed by a colon. */
+    WRAPPED_EXPR,
+    /** A miniscript expression which does not begin with wrappers. */
+    EXPR,
+
+    /** SWAP wraps the top constructed node with s: */
+    SWAP,
+    /** ALT wraps the top constructed node with a: */
+    ALT,
+    /** CHECK wraps the top constructed node with c: */
+    CHECK,
+    /** DUP_IF wraps the top constructed node with d: */
+    DUP_IF,
+    /** VERIFY wraps the top constructed node with v: */
+    VERIFY,
+    /** NON_ZERO wraps the top constructed node with j: */
+    NON_ZERO,
+    /** ZERO_NOTEQUAL wraps the top constructed node with n: */
+    ZERO_NOTEQUAL,
+    /** WRAP_U will construct an or_i(X,0) node from the top constructed node. */
+    WRAP_U,
+    /** WRAP_T will construct an and_v(X,1) node from the top constructed node. */
+    WRAP_T,
+
+    /** AND_N will construct an andor(X,Y,0) node from the last two constructed nodes. */
+    AND_N,
+    /** AND_V will construct an and_v node from the last two constructed nodes. */
+    AND_V,
+    /** AND_B will construct an and_b node from the last two constructed nodes. */
+    AND_B,
+    /** ANDOR will construct an andor node from the last three constructed nodes. */
+    ANDOR,
+    /** OR_B will construct an or_b node from the last two constructed nodes. */
+    OR_B,
+    /** OR_C will construct an or_c node from the last two constructed nodes. */
+    OR_C,
+    /** OR_D will construct an or_d node from the last two constructed nodes. */
+    OR_D,
+    /** OR_I will construct an or_i node from the last two constructed nodes. */
+    OR_I,
+
+    /** THRESH will read a wrapped expression, and then look for a COMMA. If
+     * no comma follows, it will construct a thresh node from the appropriate
+     * number of constructed children. Otherwise, it will recurse with another
+     * THRESH. */
+    THRESH,
+
+    /** COMMA expects the next element to be ',' and fails if not. */
+    COMMA,
+    /** CLOSE_BRACKET expects the next element to be ')' and fails if not. */
+    CLOSE_BRACKET,
+};
+
+int FindNextChar(Span<const char> in, const char m);
+
+/** Parse a key string ending with a ')' or ','. */
+template<typename Key, typename Ctx>
+std::optional<std::pair<Key, int>> ParseKeyEnd(Span<const char> in, const Ctx& ctx)
+{
+    Key key;
+    int key_size = FindNextChar(in, ')');
+    if (key_size < 1) return {};
+    if (!ctx.FromString(in.begin(), in.begin() + key_size, key)) return {};
+    return {{std::move(key), key_size}};
+}
+
+/** Parse a hex string ending at the end of the fragment's text representation. */
+template<typename Ctx>
+std::optional<std::pair<std::vector<unsigned char>, int>> ParseHexStrEnd(Span<const char> in, const size_t expected_size,
+                                                                         const Ctx& ctx)
+{
+    int hash_size = FindNextChar(in, ')');
+    if (hash_size < 1) return {};
+    std::string val = std::string(in.begin(), in.begin() + hash_size);
+    if (!IsHex(val)) return {};
+    auto hash = ParseHex(val);
+    if (hash.size() != expected_size) return {};
+    return {{std::move(hash), hash_size}};
+}
+
+/** BuildBack pops the last two elements off `constructed` and wraps them in the specified Fragment */
+template<typename Key>
+void BuildBack(Fragment nt, std::vector<NodeRef<Key>>& constructed, const bool reverse = false)
+{
+    NodeRef<Key> child = std::move(constructed.back());
+    constructed.pop_back();
+    if (reverse) {
+        constructed.back() = MakeNodeRef<Key>(nt, Vector(std::move(child), std::move(constructed.back())));
+    } else {
+        constructed.back() = MakeNodeRef<Key>(nt, Vector(std::move(constructed.back()), std::move(child)));
+    }
+}
+
+//! Parse a miniscript from its textual descriptor form.
+template<typename Key, typename Ctx>
+inline NodeRef<Key> Parse(Span<const char> in, const Ctx& ctx)
+{
+    using namespace spanparsing;
+
+    // The two integers are used to hold state for thresh()
+    std::vector<std::tuple<ParseContext, int64_t, int64_t>> to_parse;
+    std::vector<NodeRef<Key>> constructed;
+
+    to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+
+    while (!to_parse.empty()) {
+        // Get the current context we are decoding within
+        auto [cur_context, n, k] = to_parse.back();
+        to_parse.pop_back();
+
+        switch (cur_context) {
+        case ParseContext::WRAPPED_EXPR: {
+            int colon_index = -1;
+            for (int i = 1; i < (int)in.size(); ++i) {
+                if (in[i] == ':') {
+                    colon_index = i;
+                    break;
+                }
+                if (in[i] < 'a' || in[i] > 'z') break;
+            }
+            // If there is no colon, this loop won't execute
+            for (int j = 0; j < colon_index; ++j) {
+                if (in[j] == 'a') {
+                    to_parse.emplace_back(ParseContext::ALT, -1, -1);
+                } else if (in[j] == 's') {
+                    to_parse.emplace_back(ParseContext::SWAP, -1, -1);
+                } else if (in[j] == 'c') {
+                    to_parse.emplace_back(ParseContext::CHECK, -1, -1);
+                } else if (in[j] == 'd') {
+                    to_parse.emplace_back(ParseContext::DUP_IF, -1, -1);
+                } else if (in[j] == 'j') {
+                    to_parse.emplace_back(ParseContext::NON_ZERO, -1, -1);
+                } else if (in[j] == 'n') {
+                    to_parse.emplace_back(ParseContext::ZERO_NOTEQUAL, -1, -1);
+                } else if (in[j] == 'v') {
+                    to_parse.emplace_back(ParseContext::VERIFY, -1, -1);
+                } else if (in[j] == 'u') {
+                    to_parse.emplace_back(ParseContext::WRAP_U, -1, -1);
+                } else if (in[j] == 't') {
+                    to_parse.emplace_back(ParseContext::WRAP_T, -1, -1);
+                } else if (in[j] == 'l') {
+                    // The l: wrapper is equivalent to or_i(0,X)
+                    constructed.push_back(MakeNodeRef<Key>(Fragment::JUST_0));
+                    to_parse.emplace_back(ParseContext::OR_I, -1, -1);
+                } else {
+                    return {};
+                }
+            }
+            to_parse.emplace_back(ParseContext::EXPR, -1, -1);
+            in = in.subspan(colon_index + 1);
+            break;
+        }
+        case ParseContext::EXPR: {
+            if (Const("0", in)) {
+                constructed.push_back(MakeNodeRef<Key>(Fragment::JUST_0));
+            } else if (Const("1", in)) {
+                constructed.push_back(MakeNodeRef<Key>(Fragment::JUST_1));
+            } else if (Const("pk(", in)) {
+                auto res = ParseKeyEnd<Key, Ctx>(in, ctx);
+                if (!res) return {};
+                auto& [key, key_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::WRAP_C, Vector(MakeNodeRef<Key>(Fragment::PK_K, Vector(std::move(key))))));
+                in = in.subspan(key_size + 1);
+            } else if (Const("pkh(", in)) {
+                auto res = ParseKeyEnd<Key>(in, ctx);
+                if (!res) return {};
+                auto& [key, key_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::WRAP_C, Vector(MakeNodeRef<Key>(Fragment::PK_H, Vector(std::move(key))))));
+                in = in.subspan(key_size + 1);
+            } else if (Const("pk_k(", in)) {
+                auto res = ParseKeyEnd<Key>(in, ctx);
+                if (!res) return {};
+                auto& [key, key_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::PK_K, Vector(std::move(key))));
+                in = in.subspan(key_size + 1);
+            } else if (Const("pk_h(", in)) {
+                auto res = ParseKeyEnd<Key>(in, ctx);
+                if (!res) return {};
+                auto& [key, key_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::PK_H, Vector(std::move(key))));
+                in = in.subspan(key_size + 1);
+            } else if (Const("sha256(", in)) {
+                auto res = ParseHexStrEnd(in, 32, ctx);
+                if (!res) return {};
+                auto& [hash, hash_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::SHA256, std::move(hash)));
+                in = in.subspan(hash_size + 1);
+            } else if (Const("ripemd160(", in)) {
+                auto res = ParseHexStrEnd(in, 20, ctx);
+                if (!res) return {};
+                auto& [hash, hash_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::RIPEMD160, std::move(hash)));
+                in = in.subspan(hash_size + 1);
+            } else if (Const("hash256(", in)) {
+                auto res = ParseHexStrEnd(in, 32, ctx);
+                if (!res) return {};
+                auto& [hash, hash_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::HASH256, std::move(hash)));
+                in = in.subspan(hash_size + 1);
+            } else if (Const("hash160(", in)) {
+                auto res = ParseHexStrEnd(in, 20, ctx);
+                if (!res) return {};
+                auto& [hash, hash_size] = *res;
+                constructed.push_back(MakeNodeRef<Key>(Fragment::HASH160, std::move(hash)));
+                in = in.subspan(hash_size + 1);
+            } else if (Const("after(", in)) {
+                int arg_size = FindNextChar(in, ')');
+                if (arg_size < 1) return {};
+                int64_t num;
+                if (!ParseInt64(std::string(in.begin(), in.begin() + arg_size), &num)) return {};
+                if (num < 1 || num >= 0x80000000L) return {};
+                constructed.push_back(MakeNodeRef<Key>(Fragment::AFTER, num));
+                in = in.subspan(arg_size + 1);
+            } else if (Const("older(", in)) {
+                int arg_size = FindNextChar(in, ')');
+                if (arg_size < 1) return {};
+                int64_t num;
+                if (!ParseInt64(std::string(in.begin(), in.begin() + arg_size), &num)) return {};
+                if (num < 1 || num >= 0x80000000L) return {};
+                constructed.push_back(MakeNodeRef<Key>(Fragment::OLDER, num));
+                in = in.subspan(arg_size + 1);
+            } else if (Const("multi(", in)) {
+                // Get threshold
+                int next_comma = FindNextChar(in, ',');
+                if (next_comma < 1) return {};
+                if (!ParseInt64(std::string(in.begin(), in.begin() + next_comma), &k)) return {};
+                in = in.subspan(next_comma + 1);
+                // Get keys
+                std::vector<Key> keys;
+                while (next_comma != -1) {
+                    Key key;
+                    next_comma = FindNextChar(in, ',');
+                    int key_length = (next_comma == -1) ? FindNextChar(in, ')') : next_comma;
+                    if (key_length < 1) return {};
+                    if (!ctx.FromString(in.begin(), in.begin() + key_length, key)) return {};
+                    keys.push_back(std::move(key));
+                    in = in.subspan(key_length + 1);
+                }
+                if (keys.size() < 1 || keys.size() > 20) return {};
+                if (k < 1 || k > (int64_t)keys.size()) return {};
+                constructed.push_back(MakeNodeRef<Key>(Fragment::MULTI, std::move(keys), k));
+            } else if (Const("thresh(", in)) {
+                int next_comma = FindNextChar(in, ',');
+                if (next_comma < 1) return {};
+                if (!ParseInt64(std::string(in.begin(), in.begin() + next_comma), &k)) return {};
+                if (k < 1) return {};
+                in = in.subspan(next_comma + 1);
+                // n = 1 here because we read the first WRAPPED_EXPR before reaching THRESH
+                to_parse.emplace_back(ParseContext::THRESH, 1, k);
+                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+            } else if (Const("andor(", in)) {
+                to_parse.emplace_back(ParseContext::ANDOR, -1, -1);
+                to_parse.emplace_back(ParseContext::CLOSE_BRACKET, -1, -1);
+                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+                to_parse.emplace_back(ParseContext::COMMA, -1, -1);
+                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+                to_parse.emplace_back(ParseContext::COMMA, -1, -1);
+                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+            } else {
+                if (Const("and_n(", in)) {
+                    to_parse.emplace_back(ParseContext::AND_N, -1, -1);
+                } else if (Const("and_b(", in)) {
+                    to_parse.emplace_back(ParseContext::AND_B, -1, -1);
+                } else if (Const("and_v(", in)) {
+                    to_parse.emplace_back(ParseContext::AND_V, -1, -1);
+                } else if (Const("or_b(", in)) {
+                    to_parse.emplace_back(ParseContext::OR_B, -1, -1);
+                } else if (Const("or_c(", in)) {
+                    to_parse.emplace_back(ParseContext::OR_C, -1, -1);
+                } else if (Const("or_d(", in)) {
+                    to_parse.emplace_back(ParseContext::OR_D, -1, -1);
+                } else if (Const("or_i(", in)) {
+                    to_parse.emplace_back(ParseContext::OR_I, -1, -1);
+                } else {
+                    return {};
+                }
+                to_parse.emplace_back(ParseContext::CLOSE_BRACKET, -1, -1);
+                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+                to_parse.emplace_back(ParseContext::COMMA, -1, -1);
+                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+            }
+            break;
+        }
+        case ParseContext::ALT: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::WRAP_A, Vector(std::move(constructed.back())));
+            break;
+        }
+        case ParseContext::SWAP: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::WRAP_S, Vector(std::move(constructed.back())));
+            break;
+        }
+        case ParseContext::CHECK: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::WRAP_C, Vector(std::move(constructed.back())));
+            break;
+        }
+        case ParseContext::DUP_IF: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::WRAP_D, Vector(std::move(constructed.back())));
+            break;
+        }
+        case ParseContext::NON_ZERO: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::WRAP_J, Vector(std::move(constructed.back())));
+            break;
+        }
+        case ParseContext::ZERO_NOTEQUAL: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::WRAP_N, Vector(std::move(constructed.back())));
+            break;
+        }
+        case ParseContext::VERIFY: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::WRAP_V, Vector(std::move(constructed.back())));
+            break;
+        }
+        case ParseContext::WRAP_U: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::OR_I, Vector(std::move(constructed.back()), MakeNodeRef<Key>(Fragment::JUST_0)));
+            break;
+        }
+        case ParseContext::WRAP_T: {
+            constructed.back() = MakeNodeRef<Key>(Fragment::AND_V, Vector(std::move(constructed.back()), MakeNodeRef<Key>(Fragment::JUST_1)));
+            break;
+        }
+        case ParseContext::AND_B: {
+            BuildBack(Fragment::AND_B, constructed);
+            break;
+        }
+        case ParseContext::AND_N: {
+            auto mid = std::move(constructed.back());
+            constructed.pop_back();
+            constructed.back() = MakeNodeRef<Key>(Fragment::ANDOR, Vector(std::move(constructed.back()), std::move(mid), MakeNodeRef<Key>(Fragment::JUST_0)));
+            break;
+        }
+        case ParseContext::AND_V: {
+            BuildBack(Fragment::AND_V, constructed);
+            break;
+        }
+        case ParseContext::OR_B: {
+            BuildBack(Fragment::OR_B, constructed);
+            break;
+        }
+        case ParseContext::OR_C: {
+            BuildBack(Fragment::OR_C, constructed);
+            break;
+        }
+        case ParseContext::OR_D: {
+            BuildBack(Fragment::OR_D, constructed);
+            break;
+        }
+        case ParseContext::OR_I: {
+            BuildBack(Fragment::OR_I, constructed);
+            break;
+        }
+        case ParseContext::ANDOR: {
+            auto right = std::move(constructed.back());
+            constructed.pop_back();
+            auto mid = std::move(constructed.back());
+            constructed.pop_back();
+            constructed.back() = MakeNodeRef<Key>(Fragment::ANDOR, Vector(std::move(constructed.back()), std::move(mid), std::move(right)));
+            break;
+        }
+        case ParseContext::THRESH: {
+            if (in.size() < 1) return {};
+            if (in[0] == ',') {
+                in = in.subspan(1);
+                to_parse.emplace_back(ParseContext::THRESH, n+1, k);
+                to_parse.emplace_back(ParseContext::WRAPPED_EXPR, -1, -1);
+            } else if (in[0] == ')') {
+                if (k > n) return {};
+                in = in.subspan(1);
+                // Children are constructed in reverse order, so iterate from end to beginning
+                std::vector<NodeRef<Key>> subs;
+                for (int i = 0; i < n; ++i) {
+                    subs.push_back(std::move(constructed.back()));
+                    constructed.pop_back();
+                }
+                std::reverse(subs.begin(), subs.end());
+                constructed.push_back(MakeNodeRef<Key>(Fragment::THRESH, std::move(subs), k));
+            } else {
+                return {};
+            }
+            break;
+        }
+        case ParseContext::COMMA: {
+            if (in.size() < 1 || in[0] != ',') return {};
+            in = in.subspan(1);
+            break;
+        }
+        case ParseContext::CLOSE_BRACKET: {
+            if (in.size() < 1 || in[0] != ')') return {};
+            in = in.subspan(1);
+            break;
+        }
+        }
+    }
+
+    // Sanity checks on the produced miniscript
+    assert(constructed.size() == 1);
+    if (in.size() > 0) return {};
+    const NodeRef<Key> tl_node = std::move(constructed.front());
+    if (!tl_node->IsValidTopLevel()) return {};
+    return tl_node;
+}
+
+} // namespace internal
+
+template<typename Ctx>
+inline NodeRef<typename Ctx::Key> FromString(const std::string& str, const Ctx& ctx) {
+    return internal::Parse<typename Ctx::Key>(str, ctx);
+}
+
+} // namespace miniscript
+
+#endif // BITCOIN_SCRIPT_MINISCRIPT_H