1// Copyright 2019 The Bazel Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package resolve 6 7import "go.starlark.net/syntax" 8 9// This file defines resolver data types saved in the syntax tree. 10// We cannot guarantee API stability for these types 11// as they are closely tied to the implementation. 12 13// A Binding contains resolver information about an identifer. 14// The resolver populates the Binding field of each syntax.Identifier. 15// The Binding ties together all identifiers that denote the same variable. 16type Binding struct { 17 Scope Scope 18 19 // Index records the index into the enclosing 20 // - {DefStmt,File}.Locals, if Scope==Local 21 // - DefStmt.FreeVars, if Scope==Free 22 // - File.Globals, if Scope==Global. 23 // It is zero if Scope is Predeclared, Universal, or Undefined. 24 Index int 25 26 First *syntax.Ident // first binding use (iff Scope==Local/Free/Global) 27} 28 29// The Scope of Binding indicates what kind of scope it has. 30type Scope uint8 31 32const ( 33 Undefined Scope = iota // name is not defined 34 Local // name is local to its function or file 35 Cell // name is function-local but shared with a nested function 36 Free // name is cell of some enclosing function 37 Global // name is global to module 38 Predeclared // name is predeclared for this module (e.g. glob) 39 Universal // name is universal (e.g. len) 40) 41 42var scopeNames = [...]string{ 43 Undefined: "undefined", 44 Local: "local", 45 Cell: "cell", 46 Free: "free", 47 Global: "global", 48 Predeclared: "predeclared", 49 Universal: "universal", 50} 51 52func (scope Scope) String() string { return scopeNames[scope] } 53 54// A Module contains resolver information about a file. 55// The resolver populates the Module field of each syntax.File. 56type Module struct { 57 Locals []*Binding // the file's (comprehension-)local variables 58 Globals []*Binding // the file's global variables 59} 60 61// A Function contains resolver information about a named or anonymous function. 62// The resolver populates the Function field of each syntax.DefStmt and syntax.LambdaExpr. 63type Function struct { 64 Pos syntax.Position // of DEF or LAMBDA 65 Name string // name of def, or "lambda" 66 Params []syntax.Expr // param = ident | ident=expr | * | *ident | **ident 67 Body []syntax.Stmt // contains synthetic 'return expr' for lambda 68 69 HasVarargs bool // whether params includes *args (convenience) 70 HasKwargs bool // whether params includes **kwargs (convenience) 71 NumKwonlyParams int // number of keyword-only optional parameters 72 Locals []*Binding // this function's local/cell variables, parameters first 73 FreeVars []*Binding // enclosing cells to capture in closure 74} 75