Update: Add Fixer method to Linter API

docs/developer-guide/nodejs-api.md

@@ -147,6 +147,37 @@ console.log(code.text);     // "var foo = bar;"
 
 In this way, you can retrieve the text and AST used for the last run of `linter.verify()`.
 
+### verifyAndFix()
+
+This method is similar to verify except that it also runs autofixing logic, similar to the `--fix` flag on the command line. The result object will contain the autofixed code, along with any remaining linting messages for the code that were not autofixed.
+
+```js
+var Linter = require("eslint").Linter;
+var linter = new Linter();
+
+var messages = linter.verifyAndFix("var foo", {
+    rules: {
+        semi: 2
+    }
+}, { filename: "foo.js" });
+```
+
+Output object from this method:
+
+```js
+{
+    fixed: true,
+    text: "var foo;",
+    messages: []
+}
+```
+
+The information available is:
+
+* `fixed` - True, if the code was fixed.
+* `text` - Fixed code text (might be the same as input if no fixes were applied).
+* `messages` - Collection of all messages for the given code (It has the same information as explained above under `verify` block).
+
 ## linter
 
 The `eslint.linter` object (deprecated) is an instance of the `Linter` class as defined [above](#Linter). `eslint.linter` exists for backwards compatibility, but we do not recommend using it because any mutations to it are shared among every module that uses `eslint`. Instead, please create your own instance of `eslint.Linter`.

lib/cli-engine.js

@@ -23,11 +23,9 @@ const fs = require("fs"),
     Config = require("./config"),
     fileEntryCache = require("file-entry-cache"),
     globUtil = require("./util/glob-util"),
-    SourceCodeFixer = require("./util/source-code-fixer"),
     validator = require("./config/config-validator"),
     stringify = require("json-stable-stringify"),
     hash = require("./util/hash"),
-
     pkg = require("../package.json");
 
 const debug = require("debug")("eslint:cli-engine");
@@ -132,80 +130,6 @@ function calculateStatsPerRun(results) {
     });
 }
 
-/**
- * Performs multiple autofix passes over the text until as many fixes as possible
- * have been applied.
- * @param {string} text The source text to apply fixes to.
- * @param {Object} config The ESLint config object to use.
- * @param {Object} options The ESLint options object to use.
- * @param {string} options.filename The filename from which the text was read.
- * @param {boolean} options.allowInlineConfig Flag indicating if inline comments
- *      should be allowed.
- * @param {Linter} linter Linter context
- * @returns {Object} The result of the fix operation as returned from the
- *      SourceCodeFixer.
- * @private
- */
-function multipassFix(text, config, options, linter) {
-    const MAX_PASSES = 10;
-    let messages = [],
-        fixedResult,
-        fixed = false,
-        passNumber = 0;
-
-    /**
-     * This loop continues until one of the following is true:
-     *
-     * 1. No more fixes have been applied.
-     * 2. Ten passes have been made.
-     *
-     * That means anytime a fix is successfully applied, there will be another pass.
-     * Essentially, guaranteeing a minimum of two passes.
-     */
-    do {
-        passNumber++;
-
-        debug(`Linting code for ${options.filename} (pass ${passNumber})`);
-        messages = linter.verify(text, config, options);
-
-        debug(`Generating fixed text for ${options.filename} (pass ${passNumber})`);
-        fixedResult = SourceCodeFixer.applyFixes(linter.getSourceCode(), messages);
-
-        // stop if there are any syntax errors.
-        // 'fixedResult.output' is a empty string.
-        if (messages.length === 1 && messages[0].fatal) {
-            break;
-        }
-
-        // keep track if any fixes were ever applied - important for return value
-        fixed = fixed || fixedResult.fixed;
-
-        // update to use the fixed output instead of the original text
-        text = fixedResult.output;
-
-    } while (
-        fixedResult.fixed &&
-        passNumber < MAX_PASSES
-    );
-
-
-    /*
-     * If the last result had fixes, we need to lint again to be sure we have
-     * the most up-to-date information.
-     */
-    if (fixedResult.fixed) {
-        fixedResult.messages = linter.verify(text, config, options);
-    }
-
-
-    // ensure the last result properly reflects if fixes were done
-    fixedResult.fixed = fixed;
-    fixedResult.output = text;
-
-    return fixedResult;
-
-}
-
 /**
  * Processes an source code using ESLint.
  * @param {string} text The source code to check.
@@ -269,10 +193,10 @@ function processText(text, configHelper, filename, fix, allowInlineConfig, linte
     } else {
 
         if (fix) {
-            fixedResult = multipassFix(text, config, {
+            fixedResult = linter.verifyAndFix(text, config, {
                 filename,
                 allowInlineConfig
-            }, linter);
+            });
             messages = fixedResult.messages;
         } else {
             messages = linter.verify(text, config, {

lib/linter.js

@@ -27,9 +27,11 @@ const assert = require("assert"),
     Rules = require("./rules"),
     timing = require("./timing"),
     astUtils = require("./ast-utils"),
+    pkg = require("../package.json"),
+    SourceCodeFixer = require("./util/source-code-fixer");
 
-    pkg = require("../package.json");
-
+const debug = require("debug")("eslint:linter");
+const MAX_AUTOFIX_PASSES = 10;
 
 //------------------------------------------------------------------------------
 // Typedefs
@@ -1185,6 +1187,74 @@ class Linter extends EventEmitter {
     getDeclaredVariables(node) {
         return (this.scopeManager && this.scopeManager.getDeclaredVariables(node)) || [];
     }
+
+    /**
+     * Performs multiple autofix passes over the text until as many fixes as possible
+     * have been applied.
+     * @param {string} text The source text to apply fixes to.
+     * @param {Object} config The ESLint config object to use.
+     * @param {Object} options The ESLint options object to use.
+     * @param {string} options.filename The filename from which the text was read.
+     * @param {boolean} options.allowInlineConfig Flag indicating if inline comments
+     *      should be allowed.
+     * @returns {Object} The result of the fix operation as returned from the
+     *      SourceCodeFixer.
+     */
+    verifyAndFix(text, config, options) {
+        let messages = [],
+            fixedResult,
+            fixed = false,
+            passNumber = 0;
+
+        /**
+         * This loop continues until one of the following is true:
+         *
+         * 1. No more fixes have been applied.
+         * 2. Ten passes have been made.
+         *
+         * That means anytime a fix is successfully applied, there will be another pass.
+         * Essentially, guaranteeing a minimum of two passes.
+         */
+        do {
+            passNumber++;
+
+            debug(`Linting code for ${options.filename} (pass ${passNumber})`);
+            messages = this.verify(text, config, options);
+
+            debug(`Generating fixed text for ${options.filename} (pass ${passNumber})`);
+            fixedResult = SourceCodeFixer.applyFixes(this.getSourceCode(), messages);
+
+            // stop if there are any syntax errors.
+            // 'fixedResult.output' is a empty string.
+            if (messages.length === 1 && messages[0].fatal) {
+                break;
+            }
+
+            // keep track if any fixes were ever applied - important for return value
+            fixed = fixed || fixedResult.fixed;
+
+            // update to use the fixed output instead of the original text
+            text = fixedResult.output;
+
+        } while (
+            fixedResult.fixed &&
+            passNumber < MAX_AUTOFIX_PASSES
+        );
+
+        /*
+         * If the last result had fixes, we need to lint again to be sure we have
+         * the most up-to-date information.
+         */
+        if (fixedResult.fixed) {
+            fixedResult.messages = this.verify(text, config, options);
+        }
+
+        // ensure the last result properly reflects if fixes were done
+        fixedResult.fixed = fixed;
+        fixedResult.output = text;
+
+        return fixedResult;
+    }
 }
 
 // methods that exist on SourceCode object

tests/lib/linter.js

@@ -70,4 +70,18 @@ describe("Linter", () => {
             });
         });
     });
+
+    describe("verifyAndFix", () => {
+        it("Fixes the code", () => {
+            const linter = new Linter();
+            const messages = linter.verifyAndFix("var a", {
+                rules: {
+                    semi: 2
+                }
+            }, { filename: "test.js" });
+
+            assert.equal(messages.output, "var a;", "Fixes were applied correctly");
+            assert.isTrue(messages.fixed);
+        });
+    });
 });