prettier · rhengles · Mar 6, 2017
diff --git a/README.md b/README.md
@@ -182,6 +182,9 @@ argument is optional, and all of the defaults are shown below:
 const prettier = require("prettier");
 
 prettier.format(source, {
+  // Indent lines with tabs
+  useTabs: false,
+
   // Fit code within this line limit
   printWidth: 80,
 

diff --git a/bin/prettier.js b/bin/prettier.js
@@ -14,6 +14,7 @@ const argv = minimist(process.argv.slice(2), {
   boolean: [
     "write",
     "stdin",
+    "use-tabs",
     "single-quote",
     "bracket-spacing",
     "jsx-bracket-same-line",
@@ -120,6 +121,7 @@ function getTrailingComma() {
 }
 
 const options = {
+  useTabs: argv["use-tabs"],
   printWidth: getIntOption("print-width"),
   tabWidth: getIntOption("tab-width"),
   bracketSpacing: argv["bracket-spacing"],
@@ -183,6 +185,7 @@ if (argv["help"] || (!filepatterns.length && !stdin)) {
       "  --stdin                  Read input from stdin.\n" +
       "  --print-width <int>      Specify the length of line that the printer will wrap on. Defaults to 80.\n" +
       "  --tab-width <int>        Specify the number of spaces per indentation-level. Defaults to 2.\n" +
+      "  --use-tabs               Indent lines with tabs instead of spaces. Defaults to false.\n" +
       "  --single-quote           Use single quotes instead of double.\n" +
       "  --bracket-spacing        Put spaces between brackets. Defaults to true.\n" +
       "  --jsx-bracket-same-line  Put > on the last line. Defaults to false.\n" +

diff --git a/index.js b/index.js
@@ -72,7 +72,8 @@ function format(text, opts) {
   const ast = parse(text, opts);
   const astComments = attachComments(text, ast, opts);
   const doc = printAstToDoc(ast, opts);
-  const str = printDocToString(doc, opts.printWidth, guessLineEnding(text));
+  opts.newLine = guessLineEnding(text);
+  const str = printDocToString(doc, opts);
   ensureAllCommentsPrinted(astComments);
   return str;
 }
@@ -100,7 +101,7 @@ module.exports = {
     formatAST: function(ast, opts) {
       opts = normalizeOptions(opts);
       const doc = printAstToDoc(ast, opts);
-      const str = printDocToString(doc, opts.printWidth);
+      const str = printDocToString(doc, opts);
       return str;
     },
     // Doesn't handle shebang for now
@@ -119,7 +120,7 @@ module.exports = {
     },
     printDocToString: function(doc, opts) {
       opts = normalizeOptions(opts);
-      const str = printDocToString(doc, opts.printWidth);
+      const str = printDocToString(doc, opts);
       return str;
     }
   }

diff --git a/src/comments.js b/src/comments.js
@@ -11,6 +11,7 @@ var concat = docBuilders.concat;
 var hardline = docBuilders.hardline;
 var breakParent = docBuilders.breakParent;
 var indent = docBuilders.indent;
+var align = docBuilders.align;
 var lineSuffix = docBuilders.lineSuffix;
 var join = docBuilders.join;
 var util = require("./util");
@@ -773,7 +774,7 @@ function printDanglingComments(path, options, sameIndent) {
   if (sameIndent) {
     return join(hardline, parts);
   }
-  return indent(options.tabWidth, concat([hardline, join(hardline, parts)]));
+  return indent(concat([hardline, join(hardline, parts)]));
 }
 
 function printComments(path, print, options) {

diff --git a/src/doc-builders.js b/src/doc-builders.js
@@ -25,10 +25,16 @@ function concat(parts) {
   return { type: "concat", parts };
 }
 
-function indent(n, contents) {
+function indent(contents) {
   assertDoc(contents);
 
-  return { type: "indent", contents, n };
+  return { type: "indent", contents };
+}
+
+function align(n, contents) {
+  assertDoc(contents);
+
+  return { type: "align", contents, n };
 }
 
 function group(contents, opts) {
@@ -104,5 +110,6 @@ module.exports = {
   lineSuffixBoundary,
   breakParent,
   ifBreak,
-  indent
+  indent,
+  align
 };
diff --git a/src/doc-printer.js b/src/doc-printer.js
@@ -3,6 +3,33 @@
 const MODE_BREAK = 1;
 const MODE_FLAT = 2;
 
+function rootIndent() {
+  return {
+    indent: 0,
+    align: {
+      spaces: 0,
+      tabs: 0
+    }
+  };
+}
+
+function indent(ind) {
+  return {
+    indent: ind.indent + 1,
+    align: ind.align
+  };
+}
+
+function align(ind, n) {
+  return {
+    indent: ind.indent,
+    align: {
+      spaces: ind.align.spaces + n,
+      tabs: ind.align.tabs + (n ? 1 : 0)
+    }
+  };
+}
+
 function fits(next, restCommands, width) {
   let restIdx = restCommands.length;
   const cmds = [next];
@@ -35,7 +62,11 @@ function fits(next, restCommands, width) {
 
           break;
         case "indent":
-          cmds.push([ind + doc.n, mode, doc.contents]);
+          cmds.push([indent(ind), mode, doc.contents]);
+
+          break;
+        case "align":
+          cmds.push([align(ind, doc.n), mode, doc.contents]);
 
           break;
         case "group":
@@ -77,14 +108,17 @@ function fits(next, restCommands, width) {
   return false;
 }
 
-function printDocToString(doc, width, newLine) {
-  newLine = newLine || "\n";
-
+function printDocToString(doc, options) {
+  let width = options.printWidth;
+  let tabWidth = options.tabWidth;
+  let useTabs = options.useTabs;
+  let indentStr = useTabs ? "\t" : " ".repeat(tabWidth);
+  let newLine = options.newLine || "\n";
   let pos = 0;
   // cmds is basically a stack. We've turned a recursive call into a
   // while loop which is much faster. The while loop below adds new
   // cmds to the array instead of recursively calling `print`.
-  let cmds = [[0, MODE_BREAK, doc]];
+  let cmds = [[rootIndent(), MODE_BREAK, doc]];
   let out = [];
   let shouldRemeasure = false;
   let lineSuffix = [];
@@ -108,7 +142,11 @@ function printDocToString(doc, width, newLine) {
 
           break;
         case "indent":
-          cmds.push([ind + doc.n, mode, doc.contents]);
+          cmds.push([indent(ind), mode, doc.contents]);
+
+          break;
+        case "align":
+          cmds.push([align(ind, doc.n), mode, doc.contents]);
 
           break;
         case "group":
@@ -239,8 +277,11 @@ function printDocToString(doc, width, newLine) {
                   );
                 }
 
-                out.push(newLine + " ".repeat(ind));
-                pos = ind;
+                let lineIndent = useTabs
+                  ? indentStr.repeat(ind.indent + ind.align.tabs)
+                  : indentStr.repeat(ind.indent) + " ".repeat(ind.align.spaces);
+                out.push(newLine + lineIndent);
+                pos = ind.indent * tabWidth + ind.align.spaces;
               }
               break;
           }

diff --git a/src/options.js b/src/options.js
@@ -4,6 +4,7 @@ var validate = require("jest-validate").validate;
 var deprecatedConfig = require("./deprecated");
 
 var defaults = {
+  useTabs: false,
   tabWidth: 2,
   printWidth: 80,
   singleQuote: false,