[Pkg-mozext-commits] [adblock-plus] 434/464: Issue 427 - Desugar arrow functions to normal or bound functions

[David Prévot]

This is an automated email from the git hooks/post-receive script.

taffit pushed a commit to branch master
in repository adblock-plus.

commit 671ce37115a918bb7b5f6b120ea5a8e55ada0b14
Author: Tom Schuster <tschuster at adblockplus.org>
Date:   Mon Jun 2 13:57:43 2014 +0200

    Issue 427 - Desugar arrow functions to normal or bound functions
---
 autotest/abprewrite_source.js               |  9 ++++-
 autotest/test_abprewrite.js.expected        | 19 +++++++++
 autotest/test_abprewrite_module.js.expected | 19 +++++++++
 scripts/abprewrite.js                       | 61 ++++++++++++++++++++---------
 scripts/astDecompile.js                     |  6 +++
 5 files changed, 94 insertions(+), 20 deletions(-)

diff --git a/autotest/abprewrite_source.js b/autotest/abprewrite_source.js
index e371291..7f59f7b 100644
--- a/autotest/abprewrite_source.js
+++ b/autotest/abprewrite_source.js
@@ -36,9 +36,9 @@ for (k of fooList)
   alert(k);
 
 
-let a = function() 1;
+let a = function() { return 1; };
 let b = {
-  get foo() 1
+  get foo() { return 1; }
 };
 
 function foo()
@@ -80,3 +80,8 @@ var a = function()
     yield i;
   }
 };
+
+let x = (y) => y + 1;
+x = y => y + 1;
+x = (a, b) => this[a] + b;
+x = (a, b) => { return () => 1; }
\ No newline at end of file
diff --git a/autotest/test_abprewrite.js.expected b/autotest/test_abprewrite.js.expected
index 49d5e12..718c027 100644
--- a/autotest/test_abprewrite.js.expected
+++ b/autotest/test_abprewrite.js.expected
@@ -131,3 +131,22 @@ var a = function()
   }
   return _generatorResult10;
 };
+var x = function(y)
+{
+  return y + 1;
+};
+x = function(y)
+{
+  return y + 1;
+};
+x = function(a, b)
+{
+  return this[a] + b;
+}.bind(this);
+x = function(a, b)
+{
+  return function()
+  {
+    return 1;
+  };
+}.bind(this);
diff --git a/autotest/test_abprewrite_module.js.expected b/autotest/test_abprewrite_module.js.expected
index 5d23db2..9817960 100644
--- a/autotest/test_abprewrite_module.js.expected
+++ b/autotest/test_abprewrite_module.js.expected
@@ -134,5 +134,24 @@ require.scopes["abprewrite_source"] = (function()
     }
     return _generatorResult10;
   };
+  var x = function(y)
+  {
+    return y + 1;
+  };
+  x = function(y)
+  {
+    return y + 1;
+  };
+  x = function(a, b)
+  {
+    return this[a] + b;
+  }.bind(this);
+  x = function(a, b)
+  {
+    return function()
+    {
+      return 1;
+    };
+  }.bind(this);
   return exports;
 })();
diff --git a/scripts/abprewrite.js b/scripts/abprewrite.js
index 3b66b1b..5b84720 100644
--- a/scripts/abprewrite.js
+++ b/scripts/abprewrite.js
@@ -396,24 +396,8 @@ function modifyFunctionExpression(ast)
 {
   if (ast.expression)
   {
-    // Convert expression closures:
-    // function() foo;
-    //
-    // Change into:
-    // function()
-    // {
-    //   return foo;
-    // }
-    ast.expression = false;
-    ast.body = {
-      type: "BlockStatement",
-      body: [
-        {
-          type: "ReturnStatement",
-          argument: ast.body
-        }
-      ]
-    };
+    print("Use arrow functions instead of function expressions!\n");
+    throw new Error("Use arrow functions instead of function expressions!");
   }
 
   if (ast.generator)
@@ -459,6 +443,47 @@ function modifyFunctionDeclaration(ast)
   return modifyFunctionExpression(ast);
 }
 
+function modifyArrowExpression(ast)
+{
+  if (ast.body.type != "BlockStatement") {
+    // Convert expressions to block statements.
+    // (a) => a + 1
+    //
+    // Change into:
+    // (a) => { return a + 1; }
+    ast.body = {
+      type: "BlockStatement",
+      body: [
+        {
+          type: "ReturnStatement",
+          argument: ast.body
+        }
+      ]
+    };
+  }
+
+  // Now convert the arrow expression into a normal
+  // function expression.
+  ast.type = "FunctionExpression";
+  ast.expression = false;
+
+  // We want to avoid the .bind call if |this| isn't actually used.
+  // This is not necessarily always correct, but should be good enough.
+  var body = decompileAST(ast.body);
+  if (/((\bthis\b)|=>)/.test(body)) {
+    return {
+      type: "CallExpression",
+      callee: Member(ast, "bind"),
+      arguments: [
+        {
+          type: "ThisExpression"
+        }
+      ]
+    };
+  }
+  return ast;
+}
+
 function modifyYieldExpression(ast)
 {
   // Convert generators into functions returning arrays:
diff --git a/scripts/astDecompile.js b/scripts/astDecompile.js
index dc68d21..49143a6 100644
--- a/scripts/astDecompile.js
+++ b/scripts/astDecompile.js
@@ -249,6 +249,12 @@ function decompileFunctionExpression(ast) {
   return decompileFunctionDeclaration(ast);
 }
 
+function decompileArrowExpression(ast) {
+  let str = "(" + ast.params.map(decompileAST).join(", ") + ")";
+  str += " => " + decompileAST(ast.body);
+  return str;
+}
+
 function decompileSequenceExpression(ast) {
   return "(" + [decompileExpr(e, ast) for each (e in ast.expressions)].join(", ") + ")";
 }

-- 
Alioth's /usr/local/bin/git-commit-notice on /srv/git.debian.org/git/pkg-mozext/adblock-plus.git