diff options
Diffstat (limited to 'vendor/golang.org/x/tools/go/ssa/source.go')
| -rw-r--r-- | vendor/golang.org/x/tools/go/ssa/source.go | 293 |
1 files changed, 0 insertions, 293 deletions
diff --git a/vendor/golang.org/x/tools/go/ssa/source.go b/vendor/golang.org/x/tools/go/ssa/source.go deleted file mode 100644 index 6d2223e..0000000 --- a/vendor/golang.org/x/tools/go/ssa/source.go +++ /dev/null @@ -1,293 +0,0 @@ -// Copyright 2013 The Go 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 ssa - -// This file defines utilities for working with source positions -// or source-level named entities ("objects"). - -// TODO(adonovan): test that {Value,Instruction}.Pos() positions match -// the originating syntax, as specified. - -import ( - "go/ast" - "go/token" - "go/types" -) - -// EnclosingFunction returns the function that contains the syntax -// node denoted by path. -// -// Syntax associated with package-level variable specifications is -// enclosed by the package's init() function. -// -// Returns nil if not found; reasons might include: -// - the node is not enclosed by any function. -// - the node is within an anonymous function (FuncLit) and -// its SSA function has not been created yet -// (pkg.Build() has not yet been called). -// -func EnclosingFunction(pkg *Package, path []ast.Node) *Function { - // Start with package-level function... - fn := findEnclosingPackageLevelFunction(pkg, path) - if fn == nil { - return nil // not in any function - } - - // ...then walk down the nested anonymous functions. - n := len(path) -outer: - for i := range path { - if lit, ok := path[n-1-i].(*ast.FuncLit); ok { - for _, anon := range fn.AnonFuncs { - if anon.Pos() == lit.Type.Func { - fn = anon - continue outer - } - } - // SSA function not found: - // - package not yet built, or maybe - // - builder skipped FuncLit in dead block - // (in principle; but currently the Builder - // generates even dead FuncLits). - return nil - } - } - return fn -} - -// HasEnclosingFunction returns true if the AST node denoted by path -// is contained within the declaration of some function or -// package-level variable. -// -// Unlike EnclosingFunction, the behaviour of this function does not -// depend on whether SSA code for pkg has been built, so it can be -// used to quickly reject check inputs that will cause -// EnclosingFunction to fail, prior to SSA building. -// -func HasEnclosingFunction(pkg *Package, path []ast.Node) bool { - return findEnclosingPackageLevelFunction(pkg, path) != nil -} - -// findEnclosingPackageLevelFunction returns the Function -// corresponding to the package-level function enclosing path. -// -func findEnclosingPackageLevelFunction(pkg *Package, path []ast.Node) *Function { - if n := len(path); n >= 2 { // [... {Gen,Func}Decl File] - switch decl := path[n-2].(type) { - case *ast.GenDecl: - if decl.Tok == token.VAR && n >= 3 { - // Package-level 'var' initializer. - return pkg.init - } - - case *ast.FuncDecl: - if decl.Recv == nil && decl.Name.Name == "init" { - // Explicit init() function. - for _, b := range pkg.init.Blocks { - for _, instr := range b.Instrs { - if instr, ok := instr.(*Call); ok { - if callee, ok := instr.Call.Value.(*Function); ok && callee.Pkg == pkg && callee.Pos() == decl.Name.NamePos { - return callee - } - } - } - } - // Hack: return non-nil when SSA is not yet - // built so that HasEnclosingFunction works. - return pkg.init - } - // Declared function/method. - return findNamedFunc(pkg, decl.Name.NamePos) - } - } - return nil // not in any function -} - -// findNamedFunc returns the named function whose FuncDecl.Ident is at -// position pos. -// -func findNamedFunc(pkg *Package, pos token.Pos) *Function { - // Look at all package members and method sets of named types. - // Not very efficient. - for _, mem := range pkg.Members { - switch mem := mem.(type) { - case *Function: - if mem.Pos() == pos { - return mem - } - case *Type: - mset := pkg.Prog.MethodSets.MethodSet(types.NewPointer(mem.Type())) - for i, n := 0, mset.Len(); i < n; i++ { - // Don't call Program.Method: avoid creating wrappers. - obj := mset.At(i).Obj().(*types.Func) - if obj.Pos() == pos { - return pkg.values[obj].(*Function) - } - } - } - } - return nil -} - -// ValueForExpr returns the SSA Value that corresponds to non-constant -// expression e. -// -// It returns nil if no value was found, e.g. -// - the expression is not lexically contained within f; -// - f was not built with debug information; or -// - e is a constant expression. (For efficiency, no debug -// information is stored for constants. Use -// go/types.Info.Types[e].Value instead.) -// - e is a reference to nil or a built-in function. -// - the value was optimised away. -// -// If e is an addressable expression used in an lvalue context, -// value is the address denoted by e, and isAddr is true. -// -// The types of e (or &e, if isAddr) and the result are equal -// (modulo "untyped" bools resulting from comparisons). -// -// (Tip: to find the ssa.Value given a source position, use -// importer.PathEnclosingInterval to locate the ast.Node, then -// EnclosingFunction to locate the Function, then ValueForExpr to find -// the ssa.Value.) -// -func (f *Function) ValueForExpr(e ast.Expr) (value Value, isAddr bool) { - if f.debugInfo() { // (opt) - e = unparen(e) - for _, b := range f.Blocks { - for _, instr := range b.Instrs { - if ref, ok := instr.(*DebugRef); ok { - if ref.Expr == e { - return ref.X, ref.IsAddr - } - } - } - } - } - return -} - -// --- Lookup functions for source-level named entities (types.Objects) --- - -// Package returns the SSA Package corresponding to the specified -// type-checker package object. -// It returns nil if no such SSA package has been created. -// -func (prog *Program) Package(obj *types.Package) *Package { - return prog.packages[obj] -} - -// packageLevelValue returns the package-level value corresponding to -// the specified named object, which may be a package-level const -// (*Const), var (*Global) or func (*Function) of some package in -// prog. It returns nil if the object is not found. -// -func (prog *Program) packageLevelValue(obj types.Object) Value { - if pkg, ok := prog.packages[obj.Pkg()]; ok { - return pkg.values[obj] - } - return nil -} - -// FuncValue returns the concrete Function denoted by the source-level -// named function obj, or nil if obj denotes an interface method. -// -// TODO(adonovan): check the invariant that obj.Type() matches the -// result's Signature, both in the params/results and in the receiver. -// -func (prog *Program) FuncValue(obj *types.Func) *Function { - fn, _ := prog.packageLevelValue(obj).(*Function) - return fn -} - -// ConstValue returns the SSA Value denoted by the source-level named -// constant obj. -// -func (prog *Program) ConstValue(obj *types.Const) *Const { - // TODO(adonovan): opt: share (don't reallocate) - // Consts for const objects and constant ast.Exprs. - - // Universal constant? {true,false,nil} - if obj.Parent() == types.Universe { - return NewConst(obj.Val(), obj.Type()) - } - // Package-level named constant? - if v := prog.packageLevelValue(obj); v != nil { - return v.(*Const) - } - return NewConst(obj.Val(), obj.Type()) -} - -// VarValue returns the SSA Value that corresponds to a specific -// identifier denoting the source-level named variable obj. -// -// VarValue returns nil if a local variable was not found, perhaps -// because its package was not built, the debug information was not -// requested during SSA construction, or the value was optimized away. -// -// ref is the path to an ast.Ident (e.g. from PathEnclosingInterval), -// and that ident must resolve to obj. -// -// pkg is the package enclosing the reference. (A reference to a var -// always occurs within a function, so we need to know where to find it.) -// -// If the identifier is a field selector and its base expression is -// non-addressable, then VarValue returns the value of that field. -// For example: -// func f() struct {x int} -// f().x // VarValue(x) returns a *Field instruction of type int -// -// All other identifiers denote addressable locations (variables). -// For them, VarValue may return either the variable's address or its -// value, even when the expression is evaluated only for its value; the -// situation is reported by isAddr, the second component of the result. -// -// If !isAddr, the returned value is the one associated with the -// specific identifier. For example, -// var x int // VarValue(x) returns Const 0 here -// x = 1 // VarValue(x) returns Const 1 here -// -// It is not specified whether the value or the address is returned in -// any particular case, as it may depend upon optimizations performed -// during SSA code generation, such as registerization, constant -// folding, avoidance of materialization of subexpressions, etc. -// -func (prog *Program) VarValue(obj *types.Var, pkg *Package, ref []ast.Node) (value Value, isAddr bool) { - // All references to a var are local to some function, possibly init. - fn := EnclosingFunction(pkg, ref) - if fn == nil { - return // e.g. def of struct field; SSA not built? - } - - id := ref[0].(*ast.Ident) - - // Defining ident of a parameter? - if id.Pos() == obj.Pos() { - for _, param := range fn.Params { - if param.Object() == obj { - return param, false - } - } - } - - // Other ident? - for _, b := range fn.Blocks { - for _, instr := range b.Instrs { - if dr, ok := instr.(*DebugRef); ok { - if dr.Pos() == id.Pos() { - return dr.X, dr.IsAddr - } - } - } - } - - // Defining ident of package-level var? - if v := prog.packageLevelValue(obj); v != nil { - return v.(*Global), true - } - - return // e.g. debug info not requested, or var optimized away -} |