1 files changed, 188 insertions, 0 deletions
diff --git a/libgo/go/exp/eval/world.go b/libgo/go/exp/eval/world.go
new file mode 100644
index 000000000..02d18bd79
--- /dev/null
+++ b/libgo/go/exp/eval/world.go
@@ -0,0 +1,188 @@
+// 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.
+
+// This package is the beginning of an interpreter for Go.
+// It can run simple Go programs but does not implement
+// interface values or packages.
+package eval
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/scanner"
+	"go/token"
+	"os"
+)
+
+type World struct {
+	scope *Scope
+	frame *Frame
+}
+
+func NewWorld() *World {
+	w := new(World)
+	w.scope = universe.ChildScope()
+	w.scope.global = true // this block's vars allocate directly
+	return w
+}
+
+type Code interface {
+	// The type of the value Run returns, or nil if Run returns nil.
+	Type() Type
+
+	// Run runs the code; if the code is a single expression
+	// with a value, it returns the value; otherwise it returns nil.
+	Run() (Value, os.Error)
+}
+
+type stmtCode struct {
+	w    *World
+	code code
+}
+
+func (w *World) CompileStmtList(fset *token.FileSet, stmts []ast.Stmt) (Code, os.Error) {
+	if len(stmts) == 1 {
+		if s, ok := stmts[0].(*ast.ExprStmt); ok {
+			return w.CompileExpr(fset, s.X)
+		}
+	}
+	errors := new(scanner.ErrorVector)
+	cc := &compiler{fset, errors, 0, 0}
+	cb := newCodeBuf()
+	fc := &funcCompiler{
+		compiler:     cc,
+		fnType:       nil,
+		outVarsNamed: false,
+		codeBuf:      cb,
+		flow:         newFlowBuf(cb),
+		labels:       make(map[string]*label),
+	}
+	bc := &blockCompiler{
+		funcCompiler: fc,
+		block:        w.scope.block,
+	}
+	nerr := cc.numError()
+	for _, stmt := range stmts {
+		bc.compileStmt(stmt)
+	}
+	fc.checkLabels()
+	if nerr != cc.numError() {
+		return nil, errors.GetError(scanner.Sorted)
+	}
+	return &stmtCode{w, fc.get()}, nil
+}
+
+func (w *World) CompileDeclList(fset *token.FileSet, decls []ast.Decl) (Code, os.Error) {
+	stmts := make([]ast.Stmt, len(decls))
+	for i, d := range decls {
+		stmts[i] = &ast.DeclStmt{d}
+	}
+	return w.CompileStmtList(fset, stmts)
+}
+
+func (s *stmtCode) Type() Type { return nil }
+
+func (s *stmtCode) Run() (Value, os.Error) {
+	t := new(Thread)
+	t.f = s.w.scope.NewFrame(nil)
+	return nil, t.Try(func(t *Thread) { s.code.exec(t) })
+}
+
+type exprCode struct {
+	w    *World
+	e    *expr
+	eval func(Value, *Thread)
+}
+
+func (w *World) CompileExpr(fset *token.FileSet, e ast.Expr) (Code, os.Error) {
+	errors := new(scanner.ErrorVector)
+	cc := &compiler{fset, errors, 0, 0}
+
+	ec := cc.compileExpr(w.scope.block, false, e)
+	if ec == nil {
+		return nil, errors.GetError(scanner.Sorted)
+	}
+	var eval func(Value, *Thread)
+	switch t := ec.t.(type) {
+	case *idealIntType:
+		// nothing
+	case *idealFloatType:
+		// nothing
+	default:
+		if tm, ok := t.(*MultiType); ok && len(tm.Elems) == 0 {
+			return &stmtCode{w, code{ec.exec}}, nil
+		}
+		eval = genAssign(ec.t, ec)
+	}
+	return &exprCode{w, ec, eval}, nil
+}
+
+func (e *exprCode) Type() Type { return e.e.t }
+
+func (e *exprCode) Run() (Value, os.Error) {
+	t := new(Thread)
+	t.f = e.w.scope.NewFrame(nil)
+	switch e.e.t.(type) {
+	case *idealIntType:
+		return &idealIntV{e.e.asIdealInt()()}, nil
+	case *idealFloatType:
+		return &idealFloatV{e.e.asIdealFloat()()}, nil
+	}
+	v := e.e.t.Zero()
+	eval := e.eval
+	err := t.Try(func(t *Thread) { eval(v, t) })
+	return v, err
+}
+
+func (w *World) Compile(fset *token.FileSet, text string) (Code, os.Error) {
+	stmts, err := parser.ParseStmtList(fset, "input", text)
+	if err == nil {
+		return w.CompileStmtList(fset, stmts)
+	}
+
+	// Otherwise try as DeclList.
+	decls, err1 := parser.ParseDeclList(fset, "input", text)
+	if err1 == nil {
+		return w.CompileDeclList(fset, decls)
+	}
+
+	// Have to pick an error.
+	// Parsing as statement list admits more forms,
+	// its error is more likely to be useful.
+	return nil, err
+}
+
+type RedefinitionError struct {
+	Name string
+	Prev Def
+}
+
+func (e *RedefinitionError) String() string {
+	res := "identifier " + e.Name + " redeclared"
+	pos := e.Prev.Pos()
+	if pos.IsValid() {
+		// TODO: fix this - currently this code is not reached by the tests
+		//       need to get a file set (fset) from somewhere
+		//res += "; previous declaration at " + fset.Position(pos).String()
+		panic(0)
+	}
+	return res
+}
+
+func (w *World) DefineConst(name string, t Type, val Value) os.Error {
+	_, prev := w.scope.DefineConst(name, token.NoPos, t, val)
+	if prev != nil {
+		return &RedefinitionError{name, prev}
+	}
+	return nil
+}
+
+func (w *World) DefineVar(name string, t Type, val Value) os.Error {
+	v, prev := w.scope.DefineVar(name, token.NoPos, t)
+	if prev != nil {
+		return &RedefinitionError{name, prev}
+	}
+	v.Init = val
+	return nil
+}