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import {Parser} from "./state"
import {has} from "./util"
const pp = Parser.prototype
// Object.assign polyfill
const assign = Object.assign || function(target, ...sources) {
for (let i = 0; i < sources.length; i++) {
const source = sources[i]
for (const key in source) {
if (has(source, key)) {
target[key] = source[key]
}
}
}
return target
}
// The functions in this module keep track of declared variables in the current scope in order to detect duplicate variable names.
pp.enterFunctionScope = function() {
// var: a hash of var-declared names in the current lexical scope
// lexical: a hash of lexically-declared names in the current lexical scope
// childVar: a hash of var-declared names in all child lexical scopes of the current lexical scope (within the current function scope)
// parentLexical: a hash of lexically-declared names in all parent lexical scopes of the current lexical scope (within the current function scope)
this.scopeStack.push({var: {}, lexical: {}, childVar: {}, parentLexical: {}})
}
pp.exitFunctionScope = function() {
this.scopeStack.pop()
}
pp.enterLexicalScope = function() {
const parentScope = this.scopeStack[this.scopeStack.length - 1]
const childScope = {var: {}, lexical: {}, childVar: {}, parentLexical: {}}
this.scopeStack.push(childScope)
assign(childScope.parentLexical, parentScope.lexical, parentScope.parentLexical)
}
pp.exitLexicalScope = function() {
const childScope = this.scopeStack.pop()
const parentScope = this.scopeStack[this.scopeStack.length - 1]
assign(parentScope.childVar, childScope.var, childScope.childVar)
}
/**
* A name can be declared with `var` if there are no variables with the same name declared with `let`/`const`
* in the current lexical scope or any of the parent lexical scopes in this function.
*/
pp.canDeclareVarName = function(name) {
const currentScope = this.scopeStack[this.scopeStack.length - 1]
return !has(currentScope.lexical, name) && !has(currentScope.parentLexical, name)
}
/**
* A name can be declared with `let`/`const` if there are no variables with the same name declared with `let`/`const`
* in the current scope, and there are no variables with the same name declared with `var` in the current scope or in
* any child lexical scopes in this function.
*/
pp.canDeclareLexicalName = function(name) {
const currentScope = this.scopeStack[this.scopeStack.length - 1]
return !has(currentScope.lexical, name) && !has(currentScope.var, name) && !has(currentScope.childVar, name)
}
pp.declareVarName = function(name) {
this.scopeStack[this.scopeStack.length - 1].var[name] = true
}
pp.declareLexicalName = function(name) {
this.scopeStack[this.scopeStack.length - 1].lexical[name] = true
}
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