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authorupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
committerupstream source tree <ports@midipix.org>2015-03-15 20:14:05 -0400
commit554fd8c5195424bdbcabf5de30fdc183aba391bd (patch)
tree976dc5ab7fddf506dadce60ae936f43f58787092 /libgo/go/exp/eval/func.go
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Diffstat (limited to 'libgo/go/exp/eval/func.go')
-rw-r--r--libgo/go/exp/eval/func.go70
1 files changed, 70 insertions, 0 deletions
diff --git a/libgo/go/exp/eval/func.go b/libgo/go/exp/eval/func.go
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+++ b/libgo/go/exp/eval/func.go
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+// 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 "os"
+
+/*
+ * Virtual machine
+ */
+
+type Thread struct {
+ abort chan os.Error
+ pc uint
+ // The execution frame of this function. This remains the
+ // same throughout a function invocation.
+ f *Frame
+}
+
+type code []func(*Thread)
+
+func (i code) exec(t *Thread) {
+ opc := t.pc
+ t.pc = 0
+ l := uint(len(i))
+ for t.pc < l {
+ pc := t.pc
+ t.pc++
+ i[pc](t)
+ }
+ t.pc = opc
+}
+
+/*
+ * Code buffer
+ */
+
+type codeBuf struct {
+ instrs code
+}
+
+func newCodeBuf() *codeBuf { return &codeBuf{make(code, 0, 16)} }
+
+func (b *codeBuf) push(instr func(*Thread)) {
+ b.instrs = append(b.instrs, instr)
+}
+
+func (b *codeBuf) nextPC() uint { return uint(len(b.instrs)) }
+
+func (b *codeBuf) get() code {
+ // Freeze this buffer into an array of exactly the right size
+ a := make(code, len(b.instrs))
+ copy(a, b.instrs)
+ return code(a)
+}
+
+/*
+ * User-defined functions
+ */
+
+type evalFunc struct {
+ outer *Frame
+ frameSize int
+ code code
+}
+
+func (f *evalFunc) NewFrame() *Frame { return f.outer.child(f.frameSize) }
+
+func (f *evalFunc) Call(t *Thread) { f.code.exec(t) }