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var sourceMap = require('source-map'),
SourceMapConsumer = sourceMap.SourceMapConsumer,
SourceMapGenerator = sourceMap.SourceMapGenerator
module.exports = merge
/**
* Merge old source map and new source map and return merged.
* If old or new source map value is falsy, return another one as it is.
*
* @param {object|undefined} oldMap old source map object
* @param {object|undefined} newmap new source map object
* @return {object|undefined} merged source map object, or undefined when both old and new source map are undefined
*/
function merge(oldMap, newMap) {
if (!oldMap)
return newMap
if (!newMap)
return oldMap
var oldMapConsumer = new SourceMapConsumer(oldMap),
newMapConsumer = new SourceMapConsumer(newMap),
mergedMapGenerator = new SourceMapGenerator()
// iterate on new map and overwrite original position of new map with one of old map
newMapConsumer.eachMapping(function(m) {
// pass when `originalLine` is null.
// It occurs in case that the node does not have origin in original code.
if (m.originalLine == null)
return
var origPosInOldMap = oldMapConsumer.originalPositionFor({line: m.originalLine, column: m.originalColumn})
if (origPosInOldMap.source == null)
return
mergedMapGenerator.addMapping({
original: {
line: origPosInOldMap.line,
column: origPosInOldMap.column
},
generated: {
line: m.generatedLine,
column: m.generatedColumn
},
source: m.source,
name: m.name
})
})
var mergedMap = JSON.parse(mergedMapGenerator.toString())
mergedMap.sources = oldMap.sources
mergedMap.sourcesContent = oldMap.sourcesContent
mergedMap.sourceRoot = oldMap.sourceRoot
return mergedMap
}
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