visitor.js

   1 let stack=[]
   2 let log = false ? console.log : () => null
   3 let doit = () => null
   4
   5 const rules = {
   6   Program({body}) {body.map(walk)},
   7   VariableDeclaration({kind,declarations}) {declarations.map(walk)},
   8   VariableDeclarator({id,init}) {walk(id);if(init)walk(init)},
   9   Identifier({start,name}) {doit(name); log(start,name)},
  10   CallExpression({callee}) {walk(callee); arguments[0]['arguments'].map(walk)},
  11   NewExpression({callee}) {walk(callee); arguments[0]['arguments'].map(walk)},
  12   FunctionExpression({params,body}) {params.map(walk); walk(body)},
  13   MemberExpression({object,property}) {walk(object); walk(property)},
  14   ObjectPattern({properties}) {properties.map(walk)},
  15   ExpressionStatement({expression}) {walk(expression)},
  16   IfStatement({test,consequent}) {walk(test); walk(consequent)},
  17   BlockStatement({body}) {body.map(walk)},
  18   ReturnStatement({argument}) {if(argument)walk(argument)},
  19
  20   Literal({start,value,raw}) {log(start,raw)},
  21   AssignmentExpression({operator,left,right}) {log(operator);walk(left);walk(right)},
  22   LogicalExpression({operator,left,right}) {log(operator);walk(left);walk(right)},
  23   BinaryExpression({operator,left,right}) {log(operator);walk(left);walk(right)},
  24   UnaryExpression({operator,prefix,argument}) {log(prefix?'prefix':'suffix',operator); walk(argument)},
  25   UpdateExpression({operator,prefix,argument}) {log(prefix?'prefix':'suffix',operator); walk(argument)},
  26   ObjectExpression({properties}) {properties.map(walk)},
  27   Property({key,value}) {walk(key);walk(value)},
  28   ArrayExpression({elements}) {elements.map(walk)},
  29   ArrayPattern({elements}) {elements.map(walk)},
  30   ArrowFunctionExpression({params,body}) {params.map(walk);walk(body)},
  31   TemplateLiteral({expressions,quasis}) {quasis.map(walk);expressions.map(walk)},
  32   TemplateElement({start,end}) {log(end-start,'bytes')},
  33
  34   ForStatement({init,test,update,body}) {walk(init);walk(test);walk(update);walk(body)},
  35   ForInStatement({left,right,body}) {walk(left); walk(right); walk(body)},
  36   ForOfStatement({left,right,body}) {walk(left); walk(right); walk(body)},
  37   ChainExpression({expression}) {walk(expression)},
  38   ConditionalExpression({test,consequent,alternative}) {walk(test);walk(consequent);walk(alternative)},
  39   ContinueStatement(){},
  40   BreakStatement(){},
  41
  42   AssignmentPattern({left,right}) {walk(left);walk(right)},
  43   WhileStatement({test,body}) {walk(test);walk(body)},
  44   TryStatement({block,handler,finalizer}) {walk(block);walk(handler);walk(finalizer)},
  45   CatchClause({param,body}) {walk(param);walk(body)},
  46
  47   EmptyStatement() {},
  48   AwaitExpression({argument}) {walk(argument)},
  49   ThrowStatement({argument}) {walk(argument)},
  50   SwitchStatement({discriminant,cases}) {walk(discriminant); cases.map(walk)},
  51   SwitchCase({test,consequent}) {walk(test); consequent.map(walk)},
  52   RestElement({argument}) {walk(argument)},
  53   ImportExpression({source}) {walk(source)},
  54   FunctionDeclaration({id,params,body}) {walk(id),params.map(walk),walk(body)},
  55
  56   ThisExpression({context}) {walk(context)},
  57
  58   DoWhileStatement({test,body}) {walk(test);walk(body)},
  59   SequenceExpression({expressions}) {expressions.map(walk)},
  60
  61   SpreadElement({argument}) {walk(argument)},
  62 }
  63
  64 let each = (branch,stack) => {}
  65 function wander(mods,doit) {
  66   each = doit
  67   for (const mod of mods) {
  68     stack = [mod.file]
  69     walk(mod.tree)
  70   }
  71   each = (branch,stack) => {}
  72 }
  73 function walk(branch) {
  74   if(branch) {
  75     const type = branch?.type;
  76     stack.unshift(branch);
  77     log('PARSING',type);
  78     each(branch,stack);
  79     (rules[type]||fail)(branch);
  80     stack.shift()
  81   }
  82 }
  83 function fail(branch) {
  84   console.log('FAIL',branch)
  85 }
  86
  87 module.exports = {wander}