src/pkg/exp/eval/compiler.go

// 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 (
	"fmt"
	"go/scanner"
	"go/token"
)


type positioned interface {
	Pos() token.Position
}


// A compiler captures information used throughout an entire
// compilation.  Currently it includes only the error handler.
//
// TODO(austin) This might actually represent package level, in which
// case it should be package compiler.
type compiler struct {
	errors       scanner.ErrorHandler
	numErrors    int
	silentErrors int
}

func (a *compiler) diagAt(pos positioned, format string, args ...) {
	a.errors.Error(pos.Pos(), fmt.Sprintf(format, args))
	a.numErrors++
}

func (a *compiler) numError() int { return a.numErrors + a.silentErrors }

// The universal scope
func newUniverse() *Scope {
	sc := &Scope{nil, 0}
	sc.block = &block{
		offset: 0,
		scope: sc,
		global: true,
		defs: make(map[string]Def),
	}
	return sc
}

var universe *Scope = newUniverse()


// TODO(austin) These can all go in stmt.go now
type label struct {
	name string
	desc string
	// The PC goto statements should jump to, or nil if this label
	// cannot be goto'd (such as an anonymous for loop label).
	gotoPC *uint
	// The PC break statements should jump to, or nil if a break
	// statement is invalid.
	breakPC *uint
	// The PC continue statements should jump to, or nil if a
	// continue statement is invalid.
	continuePC *uint
	// The position where this label was resolved.  If it has not
	// been resolved yet, an invalid position.
	resolved token.Position
	// The position where this label was first jumped to.
	used token.Position
}

// A funcCompiler captures information used throughout the compilation
// of a single function body.
type funcCompiler struct {
	*compiler
	fnType *FuncType
	// Whether the out variables are named.  This affects what
	// kinds of return statements are legal.
	outVarsNamed bool
	*codeBuf
	flow   *flowBuf
	labels map[string]*label
}

// A blockCompiler captures information used throughout the compilation
// of a single block within a function.
type blockCompiler struct {
	*funcCompiler
	block *block
	// The label of this block, used for finding break and
	// continue labels.
	label *label
	// The blockCompiler for the block enclosing this one, or nil
	// for a function-level block.
	parent *blockCompiler
}