Current Dev State

static/js/ketcher2/node_modules/babel-istanbul/lib/hook.js

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+/*
+ Copyright (c) 2012, Yahoo! Inc.  All rights reserved.
+ Copyrights licensed under the New BSD License. See the accompanying LICENSE file for terms.
+ */
+
+/**
+ * provides a mechanism to transform code in the scope of `require` or `vm.createScript`.
+ * This mechanism is general and relies on a user-supplied `matcher` function that determines when transformations should be
+ * performed and a user-supplied `transformer` function that performs the actual transform.
+ * Instrumenting code for coverage is one specific example of useful hooking.
+ *
+ * Note that both the `matcher` and `transformer` must execute synchronously.
+ *
+ * For the common case of matching filesystem paths based on inclusion/ exclusion patterns, use the `matcherFor`
+ * function in the istanbul API to get a matcher.
+ *
+ * It is up to the transformer to perform processing with side-effects, such as caching, storing the original
+ * source code to disk in case of dynamically generated scripts etc. The `Store` class can help you with this.
+ *
+ * Usage
+ * -----
+ *
+ *      var hook = require('istanbul').hook,
+ *          myMatcher = function (file) { return file.match(/foo/); },
+ *          myTransformer = function (code, file) { return 'console.log("' + file + '");' + code; };
+ *
+ *      hook.hookRequire(myMatcher, myTransformer);
+ *
+ *      var foo = require('foo'); //will now print foo's module path to console
+ *
+ * @class Hook
+ * @module main
+ */
+var path = require('path'),
+    fs = require('fs'),
+    Module = require('module'),
+    vm = require('vm'),
+    originalLoaders = {},
+    originalCreateScript = vm.createScript,
+    originalRunInThisContext = vm.runInThisContext;
+
+function transformFn(matcher, transformer, verbose) {
+
+    return function (code, filename) {
+        var shouldHook = typeof filename === 'string' && matcher(path.resolve(filename)),
+            transformed,
+            changed = false;
+
+        if (shouldHook) {
+            if (verbose) {
+                console.error('Module load hook: transform [' + filename + ']');
+            }
+            try {
+                transformed = transformer(code, filename);
+                changed = true;
+            } catch (ex) {
+                console.error('Transformation error; return original code');
+                console.error(ex);
+                transformed = code;
+            }
+        } else {
+            transformed = code;
+        }
+        return { code: transformed, changed: changed };
+    };
+}
+
+function unloadRequireCache(matcher) {
+    if (matcher && typeof require !== 'undefined' && require && require.cache) {
+        Object.keys(require.cache).forEach(function (filename) {
+            if (matcher(filename)) {
+                delete require.cache[filename];
+            }
+        });
+    }
+}
+/**
+ * hooks `require` to return transformed code to the node module loader.
+ * Exceptions in the transform result in the original code being used instead.
+ * @method hookRequire
+ * @static
+ * @param matcher {Function(filePath)} a function that is called with the absolute path to the file being
+ *  `require`-d. Should return a truthy value when transformations need to be applied to the code, a falsy value otherwise
+ * @param transformer {Function(code, filePath)} a function called with the original code and the associated path of the file
+ *  from where the code was loaded. Should return the transformed code.
+ * @param options {Object} options Optional.
+ * @param {Boolean} [options.verbose] write a line to standard error every time the transformer is called
+ * @param {Function} [options.postLoadHook] a function that is called with the name of the file being
+ *  required. This is called after the require is processed irrespective of whether it was transformed.
+ */
+function hookRequire(matcher, transformer, options) {
+    options = options || {};
+    var extensions,
+        fn = transformFn(matcher, transformer, options.verbose),
+        postLoadHook = options.postLoadHook &&
+            typeof options.postLoadHook === 'function' ? options.postLoadHook : null;
+
+    extensions = options.extensions || ['.js'];
+
+    extensions.forEach(function(ext){
+        if (!(ext in originalLoaders)) { 
+            originalLoaders[ext] = Module._extensions[ext] || Module._extensions['.js'];
+        } 
+        Module._extensions[ext] = function (module, filename) {
+            var ret = fn(fs.readFileSync(filename, 'utf8'), filename);
+            if (ret.changed) {
+                module._compile(ret.code, filename);
+            } else {
+                originalLoaders[ext](module, filename);
+            }
+            if (postLoadHook) {
+                postLoadHook(filename);
+            }
+        };
+    });
+}
+/**
+ * unhook `require` to restore it to its original state.
+ * @method unhookRequire
+ * @static
+ */
+function unhookRequire() {
+    Object.keys(originalLoaders).forEach(function(ext) {
+        Module._extensions[ext] = originalLoaders[ext];
+    });
+}
+/**
+ * hooks `vm.createScript` to return transformed code out of which a `Script` object will be created.
+ * Exceptions in the transform result in the original code being used instead.
+ * @method hookCreateScript
+ * @static
+ * @param matcher {Function(filePath)} a function that is called with the filename passed to `vm.createScript`
+ *  Should return a truthy value when transformations need to be applied to the code, a falsy value otherwise
+ * @param transformer {Function(code, filePath)} a function called with the original code and the filename passed to
+ *  `vm.createScript`. Should return the transformed code.
+ * @param options {Object} options Optional.
+ * @param {Boolean} [options.verbose] write a line to standard error every time the transformer is called
+ */
+function hookCreateScript(matcher, transformer, opts) {
+    opts = opts || {};
+    var fn = transformFn(matcher, transformer, opts.verbose);
+    vm.createScript = function (code, file) {
+        var ret = fn(code, file);
+        return originalCreateScript(ret.code, file);
+    };
+}
+
+/**
+ * unhooks vm.createScript, restoring it to its original state.
+ * @method unhookCreateScript
+ * @static
+ */
+function unhookCreateScript() {
+    vm.createScript = originalCreateScript;
+}
+
+
+/**
+ * hooks `vm.runInThisContext` to return transformed code.
+ * @method hookRunInThisContext
+ * @static
+ * @param matcher {Function(filePath)} a function that is called with the filename passed to `vm.createScript`
+ *  Should return a truthy value when transformations need to be applied to the code, a falsy value otherwise
+ * @param transformer {Function(code, filePath)} a function called with the original code and the filename passed to
+ *  `vm.createScript`. Should return the transformed code.
+ * @param options {Object} options Optional.
+ * @param {Boolean} [options.verbose] write a line to standard error every time the transformer is called
+ */
+function hookRunInThisContext(matcher, transformer, opts) {
+    opts = opts || {};
+    var fn = transformFn(matcher, transformer, opts.verbose);
+    vm.runInThisContext = function (code, file) {
+        var ret = fn(code, file);
+        return originalRunInThisContext(ret.code, file);
+    };
+}
+
+/**
+ * unhooks vm.runInThisContext, restoring it to its original state.
+ * @method unhookRunInThisContext
+ * @static
+ */
+function unhookRunInThisContext() {
+    vm.runInThisContext = originalRunInThisContext;
+}
+
+
+module.exports = {
+    hookRequire: hookRequire,
+    unhookRequire: unhookRequire,
+    hookCreateScript: hookCreateScript,
+    unhookCreateScript: unhookCreateScript,
+    hookRunInThisContext : hookRunInThisContext,
+    unhookRunInThisContext : unhookRunInThisContext,
+    unloadRequireCache: unloadRequireCache
+};
+
+