Add --range-start and --range-end options to format only parts of the input

README.md

@@ -254,6 +254,8 @@ Prettier ships with a handful of customizable format options, usable in both the
 | **JSX Brackets on Same Line** - Put the `>` of a multi-line JSX element at the end of the last line instead of being alone on the next line | `false` | `--jsx-bracket-same-line` | `jsxBracketSameLine: <bool>` |
 | **Parser** - Specify which parser to use. | `babylon` | <code>--parser <flow&#124;babylon></code> | <code>parser: "<flow&#124;babylon>"</code> |
 | **Semicolons** - Print semicolons at the ends of statements.<br /><br />Valid options: <br /> - `true` - add a semicolon at the end of every statement <br /> - `false` - only add semicolons at the beginning of lines that may introduce ASI failures | `true` | `--no-semi` | `semi: <bool>` |
+| **Range Start** - Format code starting at a given character offset. The range must begin immediately before the start of a line. | `0` | `--range-start <int>` | `rangeStart: <int>` |
+| **Range End** - Format code ending at a given character offset (exclusive). The range must end immediately after the end of a line. | `Infinity` | `--range-end <int>` | `rangeEnd: <int>` |
 
 ### Excluding code from formatting
 

bin/prettier.js

@@ -33,7 +33,7 @@ const argv = minimist(process.argv.slice(2), {
     // Deprecated in 0.0.10
     "flow-parser"
   ],
-  string: ["print-width", "tab-width", "parser", "trailing-comma"],
+  string: ["print-width", "tab-width", "parser", "trailing-comma", "range-start", "range-end"],
   default: { semi: true, color: true, "bracket-spacing": true, parser: "babylon" },
   alias: { help: "h", version: "v", "list-different": "l" },
   unknown: param => {
@@ -127,6 +127,8 @@ function getTrailingComma() {
 }
 
 const options = {
+  rangeStart: getIntOption("range-start"),
+  rangeEnd: getIntOption("range-end"),
   useTabs: argv["use-tabs"],
   semi: argv["semi"],
   printWidth: getIntOption("print-width"),
@@ -217,6 +219,8 @@ if (argv["help"] || (!filepatterns.length && !stdin)) {
       "  --trailing-comma <none|es5|all>\n" +
       "                           Print trailing commas wherever possible. Defaults to none.\n" +
       "  --parser <flow|babylon>  Specify which parse to use. Defaults to babylon.\n" +
+      "  --range-start <int>      Format code starting at a given character offset. Must be at the start of a line. Defaults to 0.\n" +
+      "  --range-end <int>        Format code ending at a given character offset (exclusive). Must be at the end of a line. Defaults to Infinity.\n" +
       "  --no-color               Do not colorize error messages.\n" +
       "  --version or -v          Print Prettier version.\n" +
       "\n"

index.js

@@ -48,16 +48,45 @@ function ensureAllCommentsPrinted(astComments) {
   });
 }
 
-function format(text, opts) {
+function format(text, opts, addIndents) {
+  addIndents = addIndents || 0;
+
+  const rangeStart = opts.rangeStart;
+  const rangeEnd = Math.min(opts.rangeEnd, text.length)
+
+  if (0 < rangeStart || rangeEnd < text.length) {
+    const rangeString = text.substring(rangeStart, rangeEnd)
+    const numIndents = countIndents(rangeString, opts);
+
+    const rangeFormatted = format(rangeString, Object.assign({}, opts, {
+      rangeStart: 0,
+      rangeEnd: Infinity,
+      printWidth: opts.printWidth - numIndents * opts.tabWidth
+    }), numIndents);
+
+    return text.slice(0, rangeStart) + rangeFormatted + text.slice(rangeEnd)
+  }
+
   const ast = parser.parse(text, opts);
   const astComments = attachComments(text, ast, opts);
-  const doc = printAstToDoc(ast, opts);
+  const doc = printAstToDoc(ast, opts, addIndents)
   opts.newLine = guessLineEnding(text);
   const str = printDocToString(doc, opts);
   ensureAllCommentsPrinted(astComments);
+  // Remove extra leading newline as well as the added indentation after last newline
+  if (addIndents > 0) {
+    return str.slice(opts.newLine.length).trimRight() + opts.newLine;
+  }
   return str;
 }
 
+function countIndents(text, opts) {
+  const tabSpaces = ' '.repeat(opts.tabWidth);
+  const indentation = text.match(/^([ \t]*)/)[1].replace(/\t/g, tabSpaces);
+  const numIndents = Math.floor(indentation.length / opts.tabWidth);
+  return numIndents;
+}
+
 function formatWithShebang(text, opts) {
   if (!text.startsWith("#!")) {
     return format(text, opts);

src/options.js

@@ -4,6 +4,8 @@ var validate = require("jest-validate").validate;
 var deprecatedConfig = require("./deprecated");
 
 var defaults = {
+  rangeStart: 0,
+  rangeEnd: Infinity,
   useTabs: false,
   tabWidth: 2,
   printWidth: 80,

src/printer.js

@@ -49,18 +49,22 @@ function shouldPrintComma(options, level) {
   }
 }
 
+function hasPrettierIgnoreComment(node) {
+  return (
+    node &&
+    node.comments &&
+    node.comments.length > 0 &&
+    node.comments.some(comment => comment.value.trim() === "prettier-ignore")
+  );
+}
+
 function genericPrint(path, options, printPath, args) {
   assert.ok(path instanceof FastPath);
 
   var node = path.getValue();
 
   // Escape hatch
-  if (
-    node &&
-    node.comments &&
-    node.comments.length > 0 &&
-    node.comments.some(comment => comment.value.trim() === "prettier-ignore")
-  ) {
+  if (hasPrettierIgnoreComment(node)) {
     return options.originalText.slice(util.locStart(node), util.locEnd(node));
   }
 
@@ -4244,7 +4248,9 @@ function removeLines(doc) {
   });
 }
 
-function printAstToDoc(ast, options) {
+function printAstToDoc(ast, options, addIndents) {
+  addIndents = addIndents || 0;
+
   function printGenerically(path, args) {
     return comments.printComments(
       path,
@@ -4256,7 +4262,19 @@ function printAstToDoc(ast, options) {
 
   const doc = printGenerically(FastPath.from(ast));
   docUtils.propagateBreaks(doc);
+  if (addIndents > 0) {
+    // Add a hardline to make the indents take effect
+    // It should be removed in index.js format()
+    return addIndentsToDoc(concat([hardline, doc]), addIndents);
+  }
   return doc;
 }
 
+function addIndentsToDoc(doc, numIndents) {
+  if (numIndents <= 0) {
+    return doc;
+  }
+  return addIndentsToDoc(indent(doc), numIndents - 1);
+}
+
 module.exports = { printAstToDoc };

tests/range/__snapshots__/jsfmt.spec.js.snap

@@ -0,0 +1,24 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`range.js 1`] = `
+function ugly ( {a=1,     b     =   2     }      ) {
+  function ugly ( {a=1,     b     =   2     }      ) {
+    function ugly ( {a=1,     b     =   2     }      ) {
+             \`multiline template string
+              with too much indentation\`
+      // The [165, 246) range selects the above two lines, including the second newline
+    }
+  }
+}
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+function ugly ( {a=1,     b     =   2     }      ) {
+  function ugly ( {a=1,     b     =   2     }      ) {
+    function ugly ( {a=1,     b     =   2     }      ) {
+            \`multiline template string
+              with too much indentation\`;
+      // The [165, 246) range selects the above two lines, including the second newline
+    }
+  }
+}
+
+`;

tests/range/jsfmt.spec.js

@@ -0,0 +1 @@
+run_spec(__dirname, { rangeStart: 165, rangeEnd: 246 });

tests/range/range.js

@@ -0,0 +1,9 @@
+function ugly ( {a=1,     b     =   2     }      ) {
+  function ugly ( {a=1,     b     =   2     }      ) {
+    function ugly ( {a=1,     b     =   2     }      ) {
+             `multiline template string
+              with too much indentation`
+      // The [165, 246) range selects the above two lines, including the second newline
+    }
+  }
+}