mirror of
https://github.com/golang/go
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91 lines
1.5 KiB
Go
91 lines
1.5 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package eval
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import (
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"container/vector";
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"eval";
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)
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/*
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* Virtual machine
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*/
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type vm struct {
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pc uint;
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// The current execution frame. If execution is within a
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// block, this may be a child of the original function
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// activation frame.
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f *Frame;
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// The original function activation frame. This is used to
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// access function out args.
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activation *Frame;
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}
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type code []func(*vm)
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func (i code) exec(fr *Frame) {
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v := vm{0, fr, fr};
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l := uint(len(i));
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for v.pc < l {
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pc := v.pc;
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v.pc++;
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i[pc](&v);
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}
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}
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/*
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* Code buffer
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*/
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type codeBuf struct {
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instrs code;
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}
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func newCodeBuf() *codeBuf {
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return &codeBuf{make(code, 0, 16)};
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}
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func (b *codeBuf) push(instr func(*vm)) {
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n := len(b.instrs);
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if n >= cap(b.instrs) {
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a := make(code, n, n*2);
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for i := range b.instrs {
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a[i] = b.instrs[i];
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}
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b.instrs = a;
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}
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b.instrs = b.instrs[0:n+1];
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b.instrs[n] = instr;
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}
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func (b *codeBuf) get() code {
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// Freeze this buffer into an array of exactly the right size
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a := make(code, len(b.instrs));
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for i := range b.instrs {
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a[i] = b.instrs[i];
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}
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return code(a);
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}
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/*
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* User-defined functions
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*/
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type evalFunc struct {
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sc *Scope;
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fr *Frame;
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code code;
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}
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func (f *evalFunc) NewFrame() *Frame {
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return f.sc.NewFrame(f.fr);
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}
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func (f *evalFunc) Call(fr *Frame) {
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f.code.exec(fr);
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}
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