[javascript mode] Simplify handling of block scopes

Issue #5296

Author: marijnh

mode/javascript/javascript.js

@@ -265,22 +265,42 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
     pass.apply(null, arguments);
     return true;
   }
+  function inList(name, list) {
+    for (var v = list; v; v = v.next) if (v.name == name) return true
+    return false;
+  }
   function register(varname) {
-    function inList(list, block) {
-      for (var v = list; v; v = v.next)
-        if (v.name == varname && (block === undefined || v.block === block)) return true;
-      return false;
-    }
     var state = cx.state;
     cx.marked = "def";
     if (state.context) {
-      var block = !(cx.state.lexical.info && cx.state.lexical.info.scope === "var");
-      if (inList(state.localVars, block)) return;
-      state.localVars = {name: varname, block: block, next: state.localVars};
+      if (state.lexical.info == "var" && state.context && state.context.block) {
+        // FIXME function decls are also not block scoped
+        var newContext = registerVarScoped(varname, state.context)
+        if (newContext != null) {
+          state.context = newContext
+          return
+        }
+      } else if (!inList(varname, state.localVars)) {
+        state.localVars = new Var(varname, state.localVars)
+        return
+      }
+    }
+    // Fall through means this is global
+    if (parserConfig.globalVars && !inList(varname, state.globalVars))
+      state.globalVars = new Var(varname, state.globalVars)
+  }
+  function registerVarScoped(varname, context) {
+    if (!context) {
+      return null
+    } else if (context.block) {
+      var inner = registerVarScoped(varname, context.prev)
+      if (!inner) return null
+      if (inner == context.prev) return context
+      return new Context(inner, context.vars, true)
+    } else if (inList(varname, context.vars)) {
+      return context
     } else {
-      if (inList(state.globalVars)) return;
-      if (parserConfig.globalVars)
-        state.globalVars = {name: varname, next: state.globalVars};
+      return new Context(context.prev, new Var(varname, context.vars), false)
     }
   }
 
@@ -290,32 +310,23 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
 
   // Combinators
 
-  var defaultVars = {name: "this", next: {name: "arguments"}};
+  function Context(prev, vars, block) { this.prev = prev; this.vars = vars; this.block = block }
+  function Var(name, next) { this.name = name; this.next = next }
+
+  var defaultVars = new Var("this", new Var("arguments", null))
   function pushcontext() {
-    cx.state.context = {prev: cx.state.context, vars: cx.state.localVars};
-    cx.state.localVars = defaultVars;
+    cx.state.context = new Context(cx.state.context, cx.state.localVars, false)
+    cx.state.localVars = defaultVars
   }
   function pushblockcontext() {
-    cx.state.context = {prev: cx.state.context, vars: cx.state.localVars, block: true};
-    cx.state.localVars = defaultVars;
+    cx.state.context = new Context(cx.state.context, cx.state.localVars, true)
+    cx.state.localVars = null
   }
   function popcontext() {
-    if (cx.state.context.block) {
-      var newVars = {name: "this", next: {name: "arguments"}};
-      // drop block-scoped variables
-      for (var v = cx.state.localVars; v; v = v.next) {
-        if (!v.block) newVars = { name: v.name, scope: v.scope, next: newVars };
-      }
-      // inherit from previous scope
-      for (v = cx.state.context.vars; v; v = v.next) {
-        newVars = { name: v.name, scope: v.scope, next: newVars };
-      }
-      cx.state.localVars = newVars;
-    } else {
-      cx.state.localVars = cx.state.context.vars;
-    }
-    cx.state.context = cx.state.context.prev;
+    cx.state.localVars = cx.state.context.vars
+    cx.state.context = cx.state.context.prev
   }
+  popcontext.lex = true
   function pushlex(type, info) {
     var result = function() {
       var state = cx.state, indent = state.indented;
@@ -347,7 +358,7 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
   }
 
   function statement(type, value) {
-    if (type == "var") return cont(pushlex("vardef", { scope: value, length: value.length }), vardef, expect(";"), poplex);
+    if (type == "var") return cont(pushlex("vardef", value), vardef, expect(";"), poplex);
     if (type == "keyword a") return cont(pushlex("form"), parenExpr, statement, poplex);
     if (type == "keyword b") return cont(pushlex("form"), statement, poplex);
     if (type == "keyword d") return cx.stream.match(/^\s*$/, false) ? cont() : cont(pushlex("stat"), maybeexpression, expect(";"), poplex);
@@ -381,7 +392,7 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
         return cont(pushlex("stat"), maybelabel);
       }
     }
-    if (type == "switch") return cont(pushblockcontext, pushlex("form"), parenExpr, expect("{"), pushlex("}", "switch"),
+    if (type == "switch") return cont(pushlex("form"), parenExpr, expect("{"), pushlex("}", "switch"), pushblockcontext,
                                       block, poplex, poplex, popcontext);
     if (type == "case") return cont(expression, expect(":"));
     if (type == "default") return cont(expect(":"));
@@ -803,7 +814,7 @@ CodeMirror.defineMode("javascript", function(config, parserConfig) {
         cc: [],
         lexical: new JSLexical((basecolumn || 0) - indentUnit, 0, "block", false),
         localVars: parserConfig.localVars,
-        context: parserConfig.localVars && {vars: parserConfig.localVars},
+        context: parserConfig.localVars && new Context(null, null, false),
         indented: basecolumn || 0
       };
       if (parserConfig.globalVars && typeof parserConfig.globalVars == "object")

mode/javascript/test.js

@@ -101,6 +101,20 @@
      "}",
      "[variable j];")
 
+  MT("leaving_scope",
+     "[keyword function] [def a]() {",
+     "  {",
+     "    [keyword const] [def x] [operator =] [number 1]",
+     "    [keyword if] ([atom true]) {",
+     "      [keyword let] [def y] [operator =] [number 2]",
+     "      [keyword var] [def z] [operator =] [number 3]",
+     "      [variable console].[property log]([variable-2 x], [variable-2 y], [variable-2 z])",
+     "    }",
+     "    [variable console].[property log]([variable-2 x], [variable y], [variable-2 z])",
+     "  }",
+     "  [variable console].[property log]([variable x], [variable y], [variable-2 z])",
+     "}")
+
   MT("quotedStringAddition",
      "[keyword let] [def f] [operator =] [variable a] [operator +] [string 'fatarrow'] [operator +] [variable c];");