1 | /*
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2 | Copyright 2012-2015, Yahoo Inc.
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3 | Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
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4 | */
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5 | var path = require('path'),
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6 | vm = require('vm'),
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7 | appendTransform = require('append-transform'),
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8 | originalCreateScript = vm.createScript,
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9 | originalRunInThisContext = vm.runInThisContext,
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10 | originalRunInContext = vm.runInContext;
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11 |
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12 | function transformFn(matcher, transformer, verbose) {
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13 |
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14 | return function (code, options) {
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15 | options = options || {};
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16 | if (typeof options === 'string') {
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17 | options = { filename: options };
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18 | }
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19 |
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20 | var shouldHook = typeof options.filename === 'string' && matcher(path.resolve(options.filename)),
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21 | transformed,
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22 | changed = false;
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23 |
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24 | if (shouldHook) {
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25 | if (verbose) {
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26 | console.error('Module load hook: transform [' + options.filename + ']');
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27 | }
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28 | try {
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29 | transformed = transformer(code, options);
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30 | changed = true;
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31 | } catch (ex) {
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32 | console.error('Transformation error for', options.filename, '; return original code');
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33 | console.error(ex.message || String(ex));
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34 | if (verbose) {
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35 | console.error(ex.stack);
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36 | }
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37 | transformed = code;
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38 | }
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39 | } else {
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40 | transformed = code;
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41 | }
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42 | return { code: transformed, changed: changed };
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43 | };
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44 | }
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45 | /**
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46 | * unloads the required caches, removing all files that would have matched
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47 | * the supplied matcher.
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48 | * @param {Function} matcher - the match function that accepts a file name and
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49 | * returns if that file should be unloaded from the cache.
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50 | */
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51 | function unloadRequireCache(matcher) {
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52 | /* istanbul ignore else: impossible to test */
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53 | if (matcher && typeof require !== 'undefined' && require && require.cache) {
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54 | Object.keys(require.cache).forEach(function (filename) {
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55 | if (matcher(filename)) {
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56 | delete require.cache[filename];
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57 | }
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58 | });
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59 | }
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60 | }
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61 | /**
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62 | * hooks `require` to return transformed code to the node module loader.
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63 | * Exceptions in the transform result in the original code being used instead.
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64 | * @method hookRequire
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65 | * @static
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66 | * @param matcher {Function(filePath)} a function that is called with the absolute path to the file being
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67 | * `require`-d. Should return a truthy value when transformations need to be applied to the code, a falsy value otherwise
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68 | * @param transformer {Function(code, filePath)} a function called with the original code and the associated path of the file
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69 | * from where the code was loaded. Should return the transformed code.
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70 | * @param options {Object} options Optional.
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71 | * @param {Boolean} [options.verbose] write a line to standard error every time the transformer is called
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72 | * @param {Function} [options.postLoadHook] a function that is called with the name of the file being
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73 | * required. This is called after the require is processed irrespective of whether it was transformed.
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74 | * @returns {Function} a reset function that can be called to remove the hook
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75 | */
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76 | function hookRequire(matcher, transformer, options) {
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77 | options = options || {};
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78 | var extensions,
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79 | disable = false,
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80 | fn = transformFn(matcher, transformer, options.verbose),
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81 | postLoadHook = options.postLoadHook &&
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82 | typeof options.postLoadHook === 'function' ? options.postLoadHook : null;
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83 |
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84 | extensions = options.extensions || ['.js'];
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85 |
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86 | extensions.forEach(function(ext){
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87 | appendTransform(function (code, filename) {
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88 | if (disable) {
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89 | return code;
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90 | }
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91 | var ret = fn(code, filename);
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92 | if (postLoadHook) {
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93 | postLoadHook(filename);
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94 | }
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95 | return ret.code;
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96 | }, ext);
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97 | });
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98 |
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99 | return function () {
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100 | disable = true;
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101 | };
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102 | }
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103 | /**
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104 | * hooks `vm.createScript` to return transformed code out of which a `Script` object will be created.
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105 | * Exceptions in the transform result in the original code being used instead.
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106 | * @method hookCreateScript
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107 | * @static
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108 | * @param matcher {Function(filePath)} a function that is called with the filename passed to `vm.createScript`
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109 | * Should return a truthy value when transformations need to be applied to the code, a falsy value otherwise
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110 | * @param transformer {Function(code, filePath)} a function called with the original code and the filename passed to
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111 | * `vm.createScript`. Should return the transformed code.
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112 | * @param options {Object} options Optional.
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113 | * @param {Boolean} [options.verbose] write a line to standard error every time the transformer is called
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114 | */
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115 | function hookCreateScript(matcher, transformer, opts) {
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116 | opts = opts || {};
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117 | var fn = transformFn(matcher, transformer, opts.verbose);
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118 | vm.createScript = function (code, file) {
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119 | var ret = fn(code, file);
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120 | return originalCreateScript(ret.code, file);
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121 | };
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122 | }
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123 | /**
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124 | * unhooks vm.createScript, restoring it to its original state.
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125 | * @method unhookCreateScript
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126 | * @static
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127 | */
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128 | function unhookCreateScript() {
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129 | vm.createScript = originalCreateScript;
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130 | }
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131 | /**
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132 | * hooks `vm.runInThisContext` to return transformed code.
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133 | * @method hookRunInThisContext
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134 | * @static
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135 | * @param matcher {Function(filePath)} a function that is called with the filename passed to `vm.runInThisContext`
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136 | * Should return a truthy value when transformations need to be applied to the code, a falsy value otherwise
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137 | * @param transformer {Function(code, options)} a function called with the original code and the filename passed to
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138 | * `vm.runInThisContext`. Should return the transformed code.
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139 | * @param opts {Object} [opts={}] options
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140 | * @param {Boolean} [opts.verbose] write a line to standard error every time the transformer is called
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141 | */
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142 | function hookRunInThisContext(matcher, transformer, opts) {
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143 | opts = opts || {};
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144 | var fn = transformFn(matcher, transformer, opts.verbose);
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145 | vm.runInThisContext = function (code, options) {
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146 | var ret = fn(code, options);
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147 | return originalRunInThisContext(ret.code, options);
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148 | };
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149 | }
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150 | /**
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151 | * unhooks vm.runInThisContext, restoring it to its original state.
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152 | * @method unhookRunInThisContext
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153 | * @static
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154 | */
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155 | function unhookRunInThisContext() {
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156 | vm.runInThisContext = originalRunInThisContext;
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157 | }
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158 | /**
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159 | * hooks `vm.runInContext` to return transformed code.
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160 | * @method hookRunInContext
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161 | * @static
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162 | * @param matcher {Function(filePath)} a function that is called with the filename passed to `vm.createScript`
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163 | * Should return a truthy value when transformations need to be applied to the code, a falsy value otherwise
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164 | * @param transformer {Function(code, filePath)} a function called with the original code and the filename passed to
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165 | * `vm.createScript`. Should return the transformed code.
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166 | * @param opts {Object} [opts={}] options
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167 | * @param {Boolean} [options.verbose] write a line to standard error every time the transformer is called
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168 | */
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169 | function hookRunInContext(matcher, transformer, opts) {
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170 | opts = opts || {};
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171 | var fn = transformFn(matcher, transformer, opts.verbose);
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172 | vm.runInContext = function (code, context, file) {
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173 | var ret = fn(code, file);
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174 | var coverageVariable = opts.coverageVariable || '__coverage__';
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175 | // Refer coverage variable in context to global coverage variable.
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176 | // So that coverage data will be written in global coverage variable for unit tests run in vm.runInContext.
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177 | // If all unit tests are run in vm.runInContext, no global coverage variable will be generated.
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178 | // Thus initialize a global coverage variable here.
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179 | if (!global[coverageVariable]) {
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180 | global[coverageVariable] = {};
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181 | }
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182 | context[coverageVariable] = global[coverageVariable];
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183 | return originalRunInContext(ret.code, context, file);
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184 | };
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185 |
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186 | }
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187 | /**
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188 | * unhooks vm.runInContext, restoring it to its original state.
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189 | * @method unhookRunInContext
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190 | * @static
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191 | */
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192 | function unhookRunInContext() {
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193 | vm.runInContext = originalRunInContext;
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194 | }
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195 | /**
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196 | * istanbul-lib-hook provides mechanisms to transform code in the scope of `require`,
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197 | * `vm.createScript`, `vm.runInThisContext` etc.
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198 | *
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199 | * This mechanism is general and relies on a user-supplied `matcher` function that
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200 | * determines when transformations should be performed and a user-supplied `transformer`
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201 | * function that performs the actual transform. Instrumenting code for coverage is
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202 | * one specific example of useful hooking.
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203 | *
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204 | * Note that both the `matcher` and `transformer` must execute synchronously.
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205 | *
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206 | * @module Exports
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207 | * @example
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208 | * var hook = require('istanbul-lib-hook'),
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209 | * myMatcher = function (file) { return file.match(/foo/); },
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210 | * myTransformer = function (code, file) {
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211 | * return 'console.log("' + file + '");' + code;
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212 | * };
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213 | *
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214 | * hook.hookRequire(myMatcher, myTransformer);
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215 | * var foo = require('foo'); //will now print foo's module path to console
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216 | */
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217 | module.exports = {
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218 | hookRequire: hookRequire,
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219 | hookCreateScript: hookCreateScript,
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220 | unhookCreateScript: unhookCreateScript,
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221 | hookRunInThisContext : hookRunInThisContext,
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222 | unhookRunInThisContext : unhookRunInThisContext,
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223 | hookRunInContext : hookRunInContext,
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224 | unhookRunInContext : unhookRunInContext,
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225 | unloadRequireCache: unloadRequireCache
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226 | };
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227 |
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228 |
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