var SourceMapGenerator = require('source-map/lib/source-map-generator').SourceMapGenerator;
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var trackNodes = {
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Atrule: true,
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Selector: true,
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Declaration: true
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};
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module.exports = function generateSourceMap(handlers) {
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var map = new SourceMapGenerator();
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var line = 1;
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var column = 0;
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var generated = {
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line: 1,
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column: 0
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};
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var original = {
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line: 0, // should be zero to add first mapping
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column: 0
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};
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var sourceMappingActive = false;
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var activatedGenerated = {
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line: 1,
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column: 0
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};
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var activatedMapping = {
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generated: activatedGenerated
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};
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var handlersNode = handlers.node;
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handlers.node = function(node) {
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if (node.loc && node.loc.start && trackNodes.hasOwnProperty(node.type)) {
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var nodeLine = node.loc.start.line;
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var nodeColumn = node.loc.start.column - 1;
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if (original.line !== nodeLine ||
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original.column !== nodeColumn) {
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original.line = nodeLine;
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original.column = nodeColumn;
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generated.line = line;
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generated.column = column;
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if (sourceMappingActive) {
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sourceMappingActive = false;
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if (generated.line !== activatedGenerated.line ||
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generated.column !== activatedGenerated.column) {
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map.addMapping(activatedMapping);
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}
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}
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sourceMappingActive = true;
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map.addMapping({
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source: node.loc.source,
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original: original,
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generated: generated
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});
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}
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}
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handlersNode.call(this, node);
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if (sourceMappingActive && trackNodes.hasOwnProperty(node.type)) {
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activatedGenerated.line = line;
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activatedGenerated.column = column;
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}
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};
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var handlersChunk = handlers.chunk;
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handlers.chunk = function(chunk) {
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for (var i = 0; i < chunk.length; i++) {
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if (chunk.charCodeAt(i) === 10) { // \n
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line++;
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column = 0;
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} else {
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column++;
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}
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}
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handlersChunk(chunk);
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};
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var handlersResult = handlers.result;
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handlers.result = function() {
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if (sourceMappingActive) {
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map.addMapping(activatedMapping);
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}
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return {
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css: handlersResult(),
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map: map
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};
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};
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return handlers;
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};
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