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// Copyright 2019 The Bazel Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package resolve
import ""
// This file defines resolver data types saved in the syntax tree.
// We cannot guarantee API stability for these types
// as they are closely tied to the implementation.
// A Binding contains resolver information about an identifier.
// The resolver populates the Binding field of each syntax.Identifier.
// The Binding ties together all identifiers that denote the same variable.
type Binding struct {
Scope Scope
// Index records the index into the enclosing
// - {DefStmt,File}.Locals, if Scope==Local
// - DefStmt.FreeVars, if Scope==Free
// - File.Globals, if Scope==Global.
// It is zero if Scope is Predeclared, Universal, or Undefined.
Index int
First *syntax.Ident // first binding use (iff Scope==Local/Free/Global)
// The Scope of Binding indicates what kind of scope it has.
type Scope uint8
const (
Undefined Scope = iota // name is not defined
Local // name is local to its function or file
Cell // name is function-local but shared with a nested function
Free // name is cell of some enclosing function
Global // name is global to module
Predeclared // name is predeclared for this module (e.g. glob)
Universal // name is universal (e.g. len)
var scopeNames = [...]string{
Undefined: "undefined",
Local: "local",
Cell: "cell",
Free: "free",
Global: "global",
Predeclared: "predeclared",
Universal: "universal",
func (scope Scope) String() string { return scopeNames[scope] }
// A Module contains resolver information about a file.
// The resolver populates the Module field of each syntax.File.
type Module struct {
Locals []*Binding // the file's (comprehension-)local variables
Globals []*Binding // the file's global variables
// A Function contains resolver information about a named or anonymous function.
// The resolver populates the Function field of each syntax.DefStmt and syntax.LambdaExpr.
type Function struct {
Pos syntax.Position // of DEF or LAMBDA
Name string // name of def, or "lambda"
Params []syntax.Expr // param = ident | ident=expr | * | *ident | **ident
Body []syntax.Stmt // contains synthetic 'return expr' for lambda
HasVarargs bool // whether params includes *args (convenience)
HasKwargs bool // whether params includes **kwargs (convenience)
NumKwonlyParams int // number of keyword-only optional parameters
Locals []*Binding // this function's local/cell variables, parameters first
FreeVars []*Binding // enclosing cells to capture in closure