improve whitespace handling of code generator, reduce the use of lookaheads, add max newlines of 2 and better newline insertion for generated nodes

lib/babel/generation/buffer.js

@@ -13,13 +13,7 @@ function Buffer(position, format, opts, code) {
   this.position = position;
   this._indent  = format.indent.base;
   this.format   = format;
-  this.deopt    = false;
   this.buf      = "";
-
-  if (code.length > 100000) { // 100KB
-    this.deopt = true;
-    console.error(messages.get("codeGeneratorDeopt", opts.filename, "100KB"));
-  }
 }
 
 Buffer.prototype.get = function () {
@@ -27,7 +21,7 @@ Buffer.prototype.get = function () {
 };
 
 Buffer.prototype.getIndent = function () {
-  if (this.deopt || this.format.concise) {
+  if (this.format.compact || this.format.concise) {
     return "";
   } else {
     return repeating(this.format.indent.style, this._indent);
@@ -65,14 +59,14 @@ Buffer.prototype.keyword = function (name) {
 };
 
 Buffer.prototype.space = function () {
-  if (this.deopt) return;
+  if (this.format.compact) return;
   if (this.buf && !this.isLast(" ") && !this.isLast("\n")) {
     this.push(" ");
   }
 };
 
 Buffer.prototype.removeLast = function (cha) {
-  if (this.deopt) return;
+  if (this.format.compact) return;
   if (!this.isLast(cha)) return;
 
   this.buf = this.buf.substr(0, this.buf.length - 1);
@@ -80,7 +74,7 @@ Buffer.prototype.removeLast = function (cha) {
 };
 
 Buffer.prototype.newline = function (i, removeLast) {
-  if (this.deopt) return;
+  if (this.format.compact) return;
 
   if (this.format.concise) {
     this.space();
@@ -90,7 +84,10 @@ Buffer.prototype.newline = function (i, removeLast) {
   removeLast = removeLast || false;
 
   if (isNumber(i)) {
-    if (this.isLast("\n")) i--;
+    i = Math.min(2, i);
+
+    if (this.endsWith("{\n")) i--;
+    if (i <= 0) return;
 
     while (i > 0) {
       this._newline(removeLast);
@@ -107,6 +104,10 @@ Buffer.prototype.newline = function (i, removeLast) {
 };
 
 Buffer.prototype._newline = function (removeLast) {
+  // never allow more than two lines
+  if (this.endsWith("\n\n")) return;
+
+  // remove the last newline
   if (removeLast && this.isLast("\n")) this.removeLast("\n");
 
   this.removeLast(" ");
@@ -114,7 +115,7 @@ Buffer.prototype._newline = function (removeLast) {
 };
 
 Buffer.prototype.push = function (str, noIndent) {
-  if (!this.deopt && this._indent && !noIndent && str !== "\n") {
+  if (!this.format.compact && this._indent && !noIndent && str !== "\n") {
     // we have an indent level and we aren't pushing a newline
     var indent = this.getIndent();
 
@@ -133,8 +134,12 @@ Buffer.prototype._push = function (str) {
   this.buf += str;
 };
 
+Buffer.prototype.endsWith = function (str) {
+  return this.buf.slice(-str.length) === str;
+};
+
 Buffer.prototype.isLast = function (cha) {
-  if (this.deopt) return false;
+  if (this.format.compact) return false;
 
   var buf = this.buf;
   var last = buf[buf.length - 1];

lib/babel/generation/generators/modules.js

@@ -62,6 +62,10 @@ exports.ImportDeclaration = function (node, print) {
 
   this.push("import ");
 
+  if (node.isType) {
+    this.push("type ");
+  }
+
   var specfiers = node.specifiers;
   if (specfiers && specfiers.length) {
     var foundImportSpecifier = false;

lib/babel/generation/generators/statements.js

@@ -184,7 +184,7 @@ exports.VariableDeclaration = function (node, print, parent) {
   }
 
   var sep = ",";
-  if (!this.buffer.deopt && hasInits) {
+  if (!this.format.compact && hasInits) {
     sep += "\n" + repeating(" ", node.kind.length + 1);
   } else {
     sep += " ";

lib/babel/generation/index.js

@@ -47,16 +47,28 @@ CodeGenerator.normalizeOptions = function (code, opts) {
     if (indent && indent !== " ") style = indent;
   }
 
-  return merge({
+  var format = merge({
     parentheses: true,
     comments: opts.comments == null || opts.comments,
     concise: false,
+    compact: "auto",
     indent: {
       adjustMultilineComment: true,
       style: style,
       base: 0
     }
   }, opts.format || {});
+
+  if (format.compact === "auto") {
+    format.compact = code.length > 100000; // 100KB
+
+    if (format.compact) {
+      format.compact = true;
+      console.error(messages.get("codeGeneratorDeopt", opts.filename, "100KB"));
+    }
+  }
+
+  return format;
 };
 
 CodeGenerator.generators = {
@@ -165,10 +177,10 @@ CodeGenerator.prototype.print = function (node, parent, opts) {
 
       var needs = n.needsWhitespaceAfter;
       if (leading) needs = n.needsWhitespaceBefore;
-      lines += needs(node, parent);
+      if (needs(node, parent)) lines++;
 
       // generated nodes can't add starting file whitespace
-      if (!self.buffer.get()) lines = 0;
+      if (!self.buffer.buf) lines = 0;
     }
 
     self.newline(lines);
@@ -296,7 +308,7 @@ CodeGenerator.prototype._getComments = function (key, node) {
 };
 
 CodeGenerator.prototype._printComments = function (comments) {
-  if (this.buffer.deopt) return;
+  if (this.format.compact) return;
 
   if (!this.format.comments) return;
   if (!comments || !comments.length) return;

lib/babel/generation/node/index.js

@@ -4,9 +4,9 @@ module.exports = Node;
 
 var whitespace = require("./whitespace");
 var parens     = require("./parentheses");
-var t          = require("../../types");
 var each       = require("lodash/collection/each");
 var some       = require("lodash/collection/some");
+var t          = require("../../types");
 
 var find = function (obj, node, parent) {
   if (!obj) return;
@@ -42,14 +42,19 @@ Node.needsWhitespace = function (node, parent, type) {
     node = node.expression;
   }
 
-  var lines = find(whitespace[type].nodes, node, parent);
-  if (lines) return lines;
+  var linesInfo = find(whitespace.nodes, node, parent);
 
-  each(find(whitespace[type].list, node, parent), function (expr) {
-    lines = Node.needsWhitespace(expr, node, type);
-    if (lines) return false;
-  });
-  return lines || 0;
+  if (!linesInfo) {
+    var items = find(whitespace.list, node, parent);
+    if (items) {
+      for (var i = 0; i < items.length; i++) {
+        linesInfo = Node.needsWhitespace(items[i], node, type);
+        if (linesInfo) break;
+      }
+    }
+  }
+
+  return (linesInfo && linesInfo[type]) || 0;
 };
 
 Node.needsWhitespaceBefore = function (node, parent) {

lib/babel/generation/node/whitespace.js

@@ -1,84 +1,118 @@
 "use strict";
 
-var t        = require("../../types");
-var each     = require("lodash/collection/each");
-var map      = require("lodash/collection/map");
-var isNumber = require("lodash/lang/isNumber");
+var isBoolean = require("lodash/lang/isBoolean");
+var each      = require("lodash/collection/each");
+var map       = require("lodash/collection/map");
+var t         = require("../../types");
 
-exports.before = {
-  nodes: {
-    Property: function (node, parent) {
-      if (parent.properties[0] === node) {
-        return 1;
-      }
-    },
+var shouldWhitespace = function (node) {
+  if (t.isFunction(node)) {
+    return true;
+  } else if (t.isAssignmentExpression(node)) {
+    return shouldWhitespace(node.right);
+  } else if (t.isBinary(node)) {
+    return shouldWhitespace(node.left) || shouldWhitespace(node.right);
+  }
 
-    SpreadProperty: function (node, parent) {
-      return exports.before.nodes.Property(node, parent);
-    },
+  return false;
+};
 
-    SwitchCase: function (node, parent) {
-      if (parent.cases[0] === node) {
-        return 1;
-      }
-    },
+exports.nodes = {
+  AssignmentExpression: function (node) {
+    if (shouldWhitespace(node.right)) {
+      return {
+        before: true,
+        after: true
+      };
+    }
+  },
 
-    CallExpression: function (node) {
-      if (t.isFunction(node.callee)) {
-        return 1;
+  SwitchCase: function (node, parent) {
+    if (parent.cases[0] === node) {
+      return {
+        before: true
+      };
+    }
+  },
+
+  LogicalExpression: function (node) {
+    if (t.isFunction(node.left) || t.isFunction(node.right)) {
+      return {
+        after: true
+      };
+    }
+  },
+
+  Literal: function (node) {
+    if (node.value === "use strict") {
+      return {
+        after: true
+      };
+    }
+  },
+
+  CallExpression: function (node) {
+    if (t.isFunction(node.callee)) {
+      return {
+        before: true,
+        after: true
+      };
+    }
+  },
+
+  VariableDeclaration: function (node) {
+    for (var i = 0; i < node.declarations.length; i++) {
+      var declar = node.declarations[i];
+      var init   = declar.init;
+      if (!t.isIdentifier(init) && shouldWhitespace(init)) {
+        return {
+          before: true,
+          after: true
+        };
       }
     }
   }
 };
 
-exports.after = {
-  nodes: {
-    LogicalExpression: function (node) {
-      return t.isFunction(node.left) || t.isFunction(node.right);
-    },
+exports.nodes.Property =
+exports.nodes.SpreadProperty = function (node, parent) {
+  if (parent.properties[0] === node) {
+    return {
+      before: true
+    };
+  }
+};
 
-    AssignmentExpression: function (node) {
-      if (t.isFunction(node.right)) {
-        return 1;
-      }
-    }
+exports.list = {
+  VariableDeclaration: function (node) {
+    return map(node.declarations, "init");
   },
 
-  list: {
-    VariableDeclaration: function (node) {
-      return map(node.declarations, "init");
-    },
+  ArrayExpression: function (node) {
+    return node.elements;
+  },
 
-    ArrayExpression: function (node) {
-      return node.elements;
-    },
-
-    ObjectExpression: function (node) {
-      return node.properties;
-    }
+  ObjectExpression: function (node) {
+    return node.properties;
   }
 };
 
 each({
-  Function: 1,
-  Class: 1,
-  For: 1,
-  ArrayExpression: { after: 1 },
-  ObjectExpression: { after: 1 },
-  SwitchStatement: 1,
-  IfStatement: { before: 1 },
-  CallExpression: { after: 1 },
-  Literal: { after: 1 }
+  Function: true,
+  Class: true,
+  Loop: true,
+  LabeledStatement: true,
+  SwitchStatement: true,
+  TryStatement: true,
+  IfStatement: true
 }, function (amounts, type) {
-  if (isNumber(amounts)) {
+  if (isBoolean(amounts)) {
     amounts = { after: amounts, before: amounts };
   }
 
   each([type].concat(t.FLIPPED_ALIAS_KEYS[type] || []), function (type) {
-    each(amounts, function (amount, key) {
-      exports[key].nodes[type] = function () {
-        return amount;
-      };
-    });
+    exports.nodes[type] = function () {
+      return amounts;
+    };
   });
 });