remove old tail call transformer

lib/6to5/transformation/transformers/es6/.tail-call.js

@@ -1,116 +0,0 @@
-"use strict";
-
-var t = require("../../../types");
-
-function transformExpression(node, scope, state) {
-  if (!node) return;
-
-  return (function subTransform(node) {
-    switch (node.type) {
-      case "ConditionalExpression":
-        // any value of ternary operator can be final one
-        subTransform(node.consequent);
-        subTransform(node.alternate);
-        break;
-
-      case "LogicalExpression":
-        // only right expression can be final and so optimized
-        subTransform(node.right);
-        break;
-
-      case "SequenceExpression":
-        // only last element of sequence can be optimized
-        var seq = node.expressions;
-        subTransform(seq[seq.length - 1]);
-        break;
-
-      case "CallExpression":
-        var callee = node.callee, thisBinding;
-        var args = [callee];
-
-        // bind `this` to object in member expressions
-        if (t.isMemberExpression(callee)) {
-          var object = state.wrapSideEffect(callee.object);
-          callee.object = object.expr;
-          thisBinding = object.ref;
-        }
-
-        if (node.arguments.length > 0 || thisBinding) {
-          args.push(t.arrayExpression(node.arguments));
-        }
-
-        if (thisBinding) {
-          args.push(thisBinding);
-        }
-
-        node.callee = state.getHelperRef();
-        node.arguments = args;
-        break;
-    }
-  })(node);
-}
-
-var functionChildrenVisitor = {
-  enter: function (node, parent, scope, state) {
-    if (t.isReturnStatement(node)) {
-      // prevent entrance by current visitor
-      this.skip();
-      // transform return argument into statement if
-      // it contains tail recursion
-      transformExpression(node.argument, scope, state);
-    } else if (t.isFunction(node)) {
-      // inner function's bodies are irrelevant
-      this.skip();
-    } else if (t.isTryStatement(parent)) {
-      if (node === parent.block) {
-        // `try`-blocks can't be optimized
-        this.skip();
-      } else if (parent.finalizer && node !== parent.finalizer) {
-        // `catch` clause followed by `finally` can't be optimized
-        this.skip();
-      }
-    }
-  }
-};
-
-var functionVisitor = {
-  enter: function (node, parent, scope, state) {
-    // traverse all child nodes of this function and find `arguments` and `this`
-    scope.traverse(node, functionChildrenVisitor, state);
-
-    return this.skip();
-  }
-};
-
-exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, scope, file) {
-  var tempId, helperRef;
-
-  var state = {
-    ownerId: node.id,
-
-    getHelperRef: function () {
-      return helperRef = helperRef || file.addHelper("tail-call");
-    },
-
-    wrapSideEffect: function (node) {
-      if (t.isIdentifier(node) || t.isLiteral(node)) {
-        return {expr: node, ref: node};
-      }
-      tempId = tempId || scope.generateUidIdentifier("temp");
-      return {
-        expr: t.assignmentExpression("=", tempId, node),
-        ref: tempId
-      };
-    }
-  };
-
-  // traverse the function and look for tail recursion
-  scope.traverse(node, functionVisitor, state);
-
-  if (tempId) {
-    t.ensureBlock(node).body.unshift(t.variableDeclaration("var", [
-      t.variableDeclarator(tempId)
-    ]));
-  }
-};