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Diffstat (limited to 'libgo/go/exp/eval/scope.go')
-rw-r--r-- | libgo/go/exp/eval/scope.go | 207 |
1 files changed, 0 insertions, 207 deletions
diff --git a/libgo/go/exp/eval/scope.go b/libgo/go/exp/eval/scope.go deleted file mode 100644 index 66305de25f0..00000000000 --- a/libgo/go/exp/eval/scope.go +++ /dev/null @@ -1,207 +0,0 @@ -// Copyright 2009 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 eval - -import ( - "go/token" - "log" -) - -/* - * Blocks and scopes - */ - -// A definition can be a *Variable, *Constant, or Type. -type Def interface { - Pos() token.Pos -} - -type Variable struct { - VarPos token.Pos - // Index of this variable in the Frame structure - Index int - // Static type of this variable - Type Type - // Value of this variable. This is only used by Scope.NewFrame; - // therefore, it is useful for global scopes but cannot be used - // in function scopes. - Init Value -} - -func (v *Variable) Pos() token.Pos { - return v.VarPos -} - -type Constant struct { - ConstPos token.Pos - Type Type - Value Value -} - -func (c *Constant) Pos() token.Pos { - return c.ConstPos -} - -// A block represents a definition block in which a name may not be -// defined more than once. -type block struct { - // The block enclosing this one, including blocks in other - // scopes. - outer *block - // The nested block currently being compiled, or nil. - inner *block - // The Scope containing this block. - scope *Scope - // The Variables, Constants, and Types defined in this block. - defs map[string]Def - // The index of the first variable defined in this block. - // This must be greater than the index of any variable defined - // in any parent of this block within the same Scope at the - // time this block is entered. - offset int - // The number of Variables defined in this block. - numVars int - // If global, do not allocate new vars and consts in - // the frame; assume that the refs will be compiled in - // using defs[name].Init. - global bool -} - -// A Scope is the compile-time analogue of a Frame, which captures -// some subtree of blocks. -type Scope struct { - // The root block of this scope. - *block - // The maximum number of variables required at any point in - // this Scope. This determines the number of slots needed in - // Frame's created from this Scope at run-time. - maxVars int -} - -func (b *block) enterChild() *block { - if b.inner != nil && b.inner.scope == b.scope { - log.Panic("Failed to exit child block before entering another child") - } - sub := &block{ - outer: b, - scope: b.scope, - defs: make(map[string]Def), - offset: b.offset + b.numVars, - } - b.inner = sub - return sub -} - -func (b *block) exit() { - if b.outer == nil { - log.Panic("Cannot exit top-level block") - } - if b.outer.scope == b.scope { - if b.outer.inner != b { - log.Panic("Already exited block") - } - if b.inner != nil && b.inner.scope == b.scope { - log.Panic("Exit of parent block without exit of child block") - } - } - b.outer.inner = nil -} - -func (b *block) ChildScope() *Scope { - if b.inner != nil && b.inner.scope == b.scope { - log.Panic("Failed to exit child block before entering a child scope") - } - sub := b.enterChild() - sub.offset = 0 - sub.scope = &Scope{sub, 0} - return sub.scope -} - -func (b *block) DefineVar(name string, pos token.Pos, t Type) (*Variable, Def) { - if prev, ok := b.defs[name]; ok { - return nil, prev - } - v := b.defineSlot(t, false) - v.VarPos = pos - b.defs[name] = v - return v, nil -} - -func (b *block) DefineTemp(t Type) *Variable { return b.defineSlot(t, true) } - -func (b *block) defineSlot(t Type, temp bool) *Variable { - if b.inner != nil && b.inner.scope == b.scope { - log.Panic("Failed to exit child block before defining variable") - } - index := -1 - if !b.global || temp { - index = b.offset + b.numVars - b.numVars++ - if index >= b.scope.maxVars { - b.scope.maxVars = index + 1 - } - } - v := &Variable{token.NoPos, index, t, nil} - return v -} - -func (b *block) DefineConst(name string, pos token.Pos, t Type, v Value) (*Constant, Def) { - if prev, ok := b.defs[name]; ok { - return nil, prev - } - c := &Constant{pos, t, v} - b.defs[name] = c - return c, nil -} - -func (b *block) DefineType(name string, pos token.Pos, t Type) Type { - if _, ok := b.defs[name]; ok { - return nil - } - nt := &NamedType{pos, name, nil, true, make(map[string]Method)} - if t != nil { - nt.Complete(t) - } - b.defs[name] = nt - return nt -} - -func (b *block) Lookup(name string) (bl *block, level int, def Def) { - for b != nil { - if d, ok := b.defs[name]; ok { - return b, level, d - } - if b.outer != nil && b.scope != b.outer.scope { - level++ - } - b = b.outer - } - return nil, 0, nil -} - -func (s *Scope) NewFrame(outer *Frame) *Frame { return outer.child(s.maxVars) } - -/* - * Frames - */ - -type Frame struct { - Outer *Frame - Vars []Value -} - -func (f *Frame) Get(level int, index int) Value { - for ; level > 0; level-- { - f = f.Outer - } - return f.Vars[index] -} - -func (f *Frame) child(numVars int) *Frame { - // TODO(austin) This is probably rather expensive. All values - // require heap allocation and zeroing them when we execute a - // definition typically requires some computation. - return &Frame{f, make([]Value, numVars)} -} |