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222 lines (211 loc) · 12.6 KB
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const esprima = require( 'esprima' );
const estraverse = require( 'estraverse' );
const { replaceASTNode, generateUnusedIdentifierName } = require( './util.js' );
module.exports = function( ast ){
function findThisAndArguments( ast ){
let isThisFound = 0;
let isArgumentsFound = 0;
estraverse.traverse(
ast,
{
enter : function( astNode, parent ){
if( astNode.type === esprima.Syntax.FunctionExpression || astNode.type === esprima.Syntax.FunctionDeclaration ){
return estraverse.VisitorOption.Skip;
};
if( astNode.type === esprima.Syntax.ThisExpression ){
isThisFound = 1;
};
if( astNode.type === esprima.Syntax.Identifier && astNode.name === 'arguments' ){
isArgumentsFound = 2;
};
if( isThisFound + isArgumentsFound === 3 ){
return estraverse.VisitorOption.Break;
};
}
}
);
return isThisFound + isArgumentsFound;
};
function replaceThisAndArguments( ast, varNameOfThis, varNameOfArguments ){
estraverse.traverse(
ast,
{
enter : function( astNode, parent ){
if( astNode.type === esprima.Syntax.FunctionExpression || astNode.type === esprima.Syntax.FunctionDeclaration ){
return estraverse.VisitorOption.Skip;
};
if( astNode.type === esprima.Syntax.ThisExpression ){
astNode.type = esprima.Syntax.Identifier;
astNode.name = varNameOfThis;
};
if( astNode.type === esprima.Syntax.Identifier && astNode.name === 'arguments' ){
astNode.name = varNameOfArguments;
};
}
}
);
};
function findInconvenientASTNode( ast, errorMessage, inconvenientIfMatched, skipIfMatched ){
function testASTNodeMatches( astNode, match ){
function isMatch( astNodeTypeOrNode ){
if( typeof astNodeTypeOrNode === 'string' ){
return astNodeTypeOrNode === astNode.type;
};
for( const key in astNodeTypeOrNode ){
if( astNodeTypeOrNode[ key ] != astNode[ key ] ){ // != , not !==
return false;
};
};
return true;
};
if( Array.isArray( match ) ){
for( let i = 0, l = match.length; i < l; ++i ){
if( isMatch( match[ i ] ) ) return true;
};
return false;
} else {
return isMatch( match );
};
};
estraverse.traverse(
ast,
{
enter : function( astNode, parent ){
if( testASTNodeMatches( astNode, skipIfMatched ) ){
return estraverse.VisitorOption.Skip;
};
if( testASTNodeMatches( astNode, inconvenientIfMatched ) ){
throw new SyntaxError( errorMessage );
};
}
}
);
};
// Common AST Node
const ASTNODE_IDENTIFER_THIS = { type : esprima.Syntax.ThisExpression };
const ASTNODE_IDENTIFER_ARGUMENTS = { type : esprima.Syntax.Identifier, name : 'arguments' };
estraverse.traverse(
ast,
{
enter : function( astNode, parent ){
const parents = this.parents();
let pointer = 0, inLoopOrSwitch;
function getParentASTNode(){
++pointer;
return parents[ parents.length - pointer ];
};
if( astNode.type === esprima.Syntax.LabeledStatement ){
// continue 不可, ただし ループに出会ったら探索しない
findInconvenientASTNode(
astNode, 'Labeled Statement cannot be rewritten because it contains `continue`!',
[ esprima.Syntax.ContinueStatement ],
[ esprima.Syntax.FunctionDeclaration, esprima.Syntax.FunctionExpression,
esprima.Syntax.ForInStatement, esprima.Syntax.ForStatement, esprima.Syntax.WhileStatement ]
);
// break 不可, ただし ループ, switch に出会ったら探索しない
findInconvenientASTNode(
astNode, 'Labeled Statement cannot be rewritten because it contains a `break`!',
[ { type : esprima.Syntax.BreakStatement, label : null } ],
[ esprima.Syntax.FunctionDeclaration, esprima.Syntax.FunctionExpression,
esprima.Syntax.ForInStatement, esprima.Syntax.ForStatement, esprima.Syntax.WhileStatement, esprima.Syntax.SwitchStatement ]
);
astNode.type = esprima.Syntax.DoWhileStatement,
astNode.test = { type : esprima.Syntax.Literal, value : false, raw : '!1' },
astNode._old = astNode.label.name;
delete astNode.label;
} else if( astNode.type === esprima.Syntax.ContinueStatement && astNode.label ){
throw new SyntaxError( "Release complex Labeled Statement is unsupported! (" + astNode.label.name + "");
} else if( astNode.type === esprima.Syntax.BreakStatement && astNode.label ){
while( parent = getParentASTNode() ){
switch( parent.type ){
case esprima.Syntax.ForInStatement : // for( in )
// case esprima.Syntax.ForOfStatement : // for( of )
case esprima.Syntax.ForStatement : // for( ;; )
case esprima.Syntax.WhileStatement : // while()
case esprima.Syntax.SwitchStatement :
inLoopOrSwitch = true;
break;
case esprima.Syntax.FunctionExpression :
if( parent._old === astNode.label.name ){
astNode.type = esprima.Syntax.ReturnStatement; // return <= break ID
astNode.argument = null; // ?
astNode._old = parent._old;
delete astNode.label;
return;
};
throw new SyntaxError( "Release complex Labeled Statement is unsupported! (" + astNode.label.name + ":{ function(){} }");
case esprima.Syntax.DoWhileStatement :
if( parent._old !== astNode.label.name ){
inLoopOrSwitch = true;
} else {
if( inLoopOrSwitch ){
// return 不可、但し、function 以下は探索しない
findInconvenientASTNode(
parent, 'Labeled Statement cannot be rewritten because it contains a `return`!',
[ { type : esprima.Syntax.ReturnStatement, _old : undefined } ], // break a => retuan は除く
[ esprima.Syntax.FunctionDeclaration, esprima.Syntax.FunctionExpression ]
);
const doWhileToFunc = parent;
delete doWhileToFunc.test;
doWhileToFunc.type = esprima.Syntax.FunctionExpression;
doWhileToFunc.id = null;
doWhileToFunc.generator = doWhileToFunc.expression = doWhileToFunc.async = false;
if( doWhileToFunc.body.type !== esprima.Syntax.BlockStatement ){
doWhileToFunc.body = { type : esprima.Syntax.BlockStatement, body : doWhileToFunc.body };
};
// 1. this, arguments キーワードを見つけたら、(function(a,b){})(this, arguments)
// 2. body 以下に (function(){}).call(this,) があった場合、その Call パラメータまでを書き換えて以下は探索しない
const isThisAndArgumentsFound = findThisAndArguments( doWhileToFunc.body );
let variableOfThis, variableOfArguments;
if( isThisAndArgumentsFound ){
// 3. 短い未使用の Indentifer を求める
variableOfThis = ( isThisAndArgumentsFound & 1 ) && generateUnusedIdentifierName( doWhileToFunc.body );
variableOfArguments = ( isThisAndArgumentsFound & 2 ) && generateUnusedIdentifierName( doWhileToFunc.body );
// 4. this, arguments を夫々に書き換える
replaceThisAndArguments( doWhileToFunc.body, variableOfThis, variableOfArguments );
};
doWhileToFunc.params =
isThisAndArgumentsFound === 0
? [] :
isThisAndArgumentsFound === 1
? [ { type : esprima.Syntax.Identifier, name : variableOfThis } ] :
isThisAndArgumentsFound === 2
? [ { type : esprima.Syntax.Identifier, name : variableOfArguments } ]
: [ { type : esprima.Syntax.Identifier, name : variableOfThis },
{ type : esprima.Syntax.Identifier, name : variableOfArguments } ];
// do{ break; }while(false)
// ↓
// (function(){ return; })()
replaceASTNode(
getParentASTNode(),
doWhileToFunc,
{
type : esprima.Syntax.ExpressionStatement,
expression : {
type : esprima.Syntax.CallExpression,
callee : doWhileToFunc,
arguments :
isThisAndArgumentsFound === 0
? [] :
isThisAndArgumentsFound === 1
? [ ASTNODE_IDENTIFER_THIS ] :
isThisAndArgumentsFound === 2
? [ ASTNODE_IDENTIFER_ARGUMENTS ]
: [ ASTNODE_IDENTIFER_THIS, ASTNODE_IDENTIFER_ARGUMENTS ]
}
}
);
astNode.type = esprima.Syntax.ReturnStatement; // return <= break ID
astNode.argument = null; // ?
astNode._old = parent._old;
};
delete astNode.label;
return;
};
};
};
};
}
}
);
};