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go/usr/gri/gosrc/parser.go
Robert Griesemer 5fc7919147 Experiments with "export":
Allow "export" keyword in front of a declaration. Semantics:
export *top-level* identifiers declared (but not the fields
of a struct type for instance).

R=r
OCL=13464
CL=13464
2008-07-25 11:27:13 -07:00

1736 lines
33 KiB
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 Parser
import Scanner "scanner"
import Globals "globals"
import Object "object"
import Type "type"
import Universe "universe"
import AST "ast"
// So I can submit and have a running parser for now...
const EnableSemanticTests = false;
export Parser
type Parser struct {
comp *Globals.Compilation;
verbose, indent int;
S *Scanner.Scanner;
// Token
tok int; // one token look-ahead
pos int; // token source position
val string; // token value (for IDENT, NUMBER, STRING only)
// Semantic analysis
top_scope *Globals.Scope;
exports *Globals.List;
}
// ----------------------------------------------------------------------------
// Support functions
func (P *Parser) PrintIndent() {
for i := P.indent; i > 0; i-- {
print ". ";
}
}
func (P *Parser) Trace(msg string) {
if P.verbose > 0 {
P.PrintIndent();
print msg, " {\n";
P.indent++;
}
}
func (P *Parser) Ecart() {
if P.verbose > 0 {
P.indent--;
P.PrintIndent();
print "}\n";
}
}
func (P *Parser) Next() {
P.tok, P.pos, P.val = P.S.Scan();
if P.verbose > 1 {
P.PrintIndent();
print "[", P.pos, "] ", Scanner.TokenName(P.tok), "\n";
}
}
func (P *Parser) Open(comp *Globals.Compilation, S *Scanner.Scanner, verbose int) {
P.comp = comp;
P.verbose = verbose;
P.indent = 0;
P.S = S;
P.Next();
P.top_scope = Universe.scope;
P.exports = Globals.NewList();
}
func (P *Parser) Error(pos int, msg string) {
P.S.Error(pos, msg);
}
func (P *Parser) Expect(tok int) {
if P.tok != tok {
P.Error(P.pos, "expected '" + Scanner.TokenName(tok) + "', found '" + Scanner.TokenName(P.tok) + "'");
}
P.Next(); // make progress in any case
}
func (P *Parser) Optional(tok int) {
if P.tok == tok {
P.Next();
}
}
// ----------------------------------------------------------------------------
// Scopes
func (P *Parser) OpenScope() {
P.top_scope = Globals.NewScope(P.top_scope);
}
func (P *Parser) CloseScope() {
P.top_scope = P.top_scope.parent;
}
func (P *Parser) Lookup(ident string) *Globals.Object {
for scope := P.top_scope; scope != nil; scope = scope.parent {
obj := scope.Lookup(ident);
if obj != nil {
return obj;
}
}
return nil;
}
func (P *Parser) DeclareInScope(scope *Globals.Scope, obj *Globals.Object) {
if EnableSemanticTests && scope.Lookup(obj.ident) != nil {
P.Error(obj.pos, `"` + obj.ident + `" is declared already`);
return; // don't insert it into the scope
}
scope.Insert(obj);
}
func (P *Parser) Declare(obj *Globals.Object) {
P.DeclareInScope(P.top_scope, obj);
}
// ----------------------------------------------------------------------------
// Common productions
func (P *Parser) TryType() *Globals.Type;
func (P *Parser) ParseExpression();
func (P *Parser) TryStatement() bool;
func (P *Parser) ParseDeclaration();
func (P *Parser) ParseIdent() string {
P.Trace("Ident");
ident := "";
if P.tok == Scanner.IDENT {
ident = P.val;
if P.verbose > 0 {
P.PrintIndent();
print "Ident = \"", ident, "\"\n";
}
P.Next();
} else {
P.Expect(Scanner.IDENT); // use Expect() error handling
}
P.Ecart();
return ident;
}
func (P *Parser) ParseIdentDecl(kind int) *Globals.Object {
P.Trace("IdentDecl");
pos := P.pos;
obj := Globals.NewObject(pos, kind, P.ParseIdent());
P.Declare(obj);
P.Ecart();
return obj;
}
func (P *Parser) ParseIdentDeclList(kind int) *Globals.List {
P.Trace("IdentDeclList");
list := Globals.NewList();
list.AddObj(P.ParseIdentDecl(kind));
for P.tok == Scanner.COMMA {
P.Next();
list.AddObj(P.ParseIdentDecl(kind));
}
P.Ecart();
return list;
}
func (P *Parser) ParseIdentList() {
P.Trace("IdentList");
P.ParseIdent();
for P.tok == Scanner.COMMA {
P.Next();
P.ParseIdent();
}
P.Ecart();
}
func (P *Parser) ParseQualifiedIdent(pos int, ident string) *Globals.Object {
P.Trace("QualifiedIdent");
if pos < 0 {
pos = P.pos;
ident = P.ParseIdent();
}
if EnableSemanticTests {
obj := P.Lookup(ident);
if obj == nil {
P.Error(pos, `"` + ident + `" is not declared`);
obj = Globals.NewObject(pos, Object.BAD, ident);
}
if obj.kind == Object.PACKAGE && P.tok == Scanner.PERIOD {
panic "Qualified ident not complete yet";
P.Next();
P.ParseIdent();
}
P.Ecart();
return obj;
} else {
if P.tok == Scanner.PERIOD {
P.Next();
P.ParseIdent();
}
P.Ecart();
return nil;
}
}
// ----------------------------------------------------------------------------
// Types
func (P *Parser) ParseType() *Globals.Type{
P.Trace("Type");
typ := P.TryType();
if typ == nil {
P.Error(P.pos, "type expected");
typ = Universe.bad_t;
}
P.Ecart();
return typ;
}
func (P *Parser) ParseTypeName() *Globals.Type {
P.Trace("TypeName");
if EnableSemanticTests {
obj := P.ParseQualifiedIdent(-1, "");
typ := obj.typ;
if obj.kind != Object.TYPE {
P.Error(obj.pos, `"` + obj.ident + `" is not a type`);
typ = Universe.bad_t;
}
P.Ecart();
return typ;
} else {
P.ParseQualifiedIdent(-1, "");
P.Ecart();
return Universe.bad_t;
}
}
func (P *Parser) ParseArrayType() *Globals.Type {
P.Trace("ArrayType");
P.Expect(Scanner.LBRACK);
typ := Globals.NewType(Type.ARRAY);
if P.tok != Scanner.RBRACK {
// TODO set typ.len_
P.ParseExpression();
}
P.Expect(Scanner.RBRACK);
typ.elt = P.ParseType();
P.Ecart();
return typ;
}
func (P *Parser) ParseChannelType() *Globals.Type {
P.Trace("ChannelType");
P.Expect(Scanner.CHAN);
typ := Globals.NewType(Type.CHANNEL);
switch P.tok {
case Scanner.SEND:
typ.flags = Type.SEND;
P.Next();
case Scanner.RECV:
typ.flags = Type.RECV;
P.Next();
default:
typ.flags = Type.SEND + Type.RECV;
}
typ.elt = P.ParseType();
P.Ecart();
return typ;
}
func (P *Parser) ParseVarDeclList() {
P.Trace("VarDeclList");
list := P.ParseIdentDeclList(Object.VAR);
typ := P.ParseType(); // TODO should check completeness of types
for p := list.first; p != nil; p = p.next {
p.obj.typ = typ; // TODO should use/have set_type()
}
P.Ecart();
}
func (P *Parser) ParseParameterSection() {
P.Trace("ParameterSection");
P.ParseVarDeclList();
P.Ecart();
}
func (P *Parser) ParseParameterList() {
P.Trace("ParameterList");
P.ParseParameterSection();
for P.tok == Scanner.COMMA {
P.Next();
P.ParseParameterSection();
}
P.Ecart();
}
func (P *Parser) ParseParameters() {
P.Trace("Parameters");
P.Expect(Scanner.LPAREN);
if P.tok != Scanner.RPAREN {
P.ParseParameterList();
}
P.Expect(Scanner.RPAREN);
P.Ecart();
}
func (P *Parser) TryResult() bool {
P.Trace("Result (try)");
res := false;
if P.tok == Scanner.LPAREN {
// TODO: here we allow empty returns - should proably fix this
P.ParseParameters();
res = true;
} else {
res = P.TryType() != nil;
}
P.Ecart();
return res;
}
func MakeFunctionType(sig *Globals.Scope, p0, r0 int, check_recv bool) *Globals.Type {
// Determine if we have a receiver or not.
if p0 > 0 && check_recv {
// method
if p0 != 1 {
panic "p0 != 1";
}
}
typ := Globals.NewType(Type.FUNCTION);
if p0 == 0 {
typ.flags = 0;
} else {
typ.flags = Type.RECV;
}
typ.len_ = r0 - p0;
typ.scope = sig;
return typ;
}
// Anonymous signatures
//
// (params)
// (params) type
// (params) (results)
// (recv) . (params)
// (recv) . (params) type
// (recv) . (params) (results)
func (P *Parser) ParseAnonymousSignature() *Globals.Type {
P.Trace("AnonymousSignature");
P.OpenScope();
sig := P.top_scope;
p0 := 0;
recv_pos := P.pos;
P.ParseParameters();
if P.tok == Scanner.PERIOD {
p0 = sig.entries.len_;
if (p0 != 1) {
P.Error(recv_pos, "must have exactly one receiver")
panic "UNIMPLEMENTED";
// TODO do something useful here
}
P.Next();
P.ParseParameters();
}
r0 := sig.entries.len_;
P.TryResult();
P.CloseScope();
P.Ecart();
return MakeFunctionType(sig, p0, r0, true);
}
// Named signatures
//
// name (params)
// name (params) type
// name (params) (results)
// (recv) name (params)
// (recv) name (params) type
// (recv) name (params) (results)
func (P *Parser) ParseNamedSignature() (name string, typ *Globals.Type) {
P.Trace("NamedSignature");
P.OpenScope();
sig := P.top_scope;
p0 := 0;
if P.tok == Scanner.LPAREN {
recv_pos := P.pos;
P.ParseParameters();
p0 = sig.entries.len_;
if (p0 != 1) {
print "p0 = ", p0, "\n";
P.Error(recv_pos, "must have exactly one receiver")
panic "UNIMPLEMENTED";
// TODO do something useful here
}
}
name = P.ParseIdent();
P.ParseParameters();
r0 := sig.entries.len_;
P.TryResult();
P.CloseScope();
P.Ecart();
return name, MakeFunctionType(sig, p0, r0, true);
}
func (P *Parser) ParseFunctionType() *Globals.Type {
P.Trace("FunctionType");
P.Expect(Scanner.FUNC);
typ := P.ParseAnonymousSignature();
P.Ecart();
return typ;
}
func (P *Parser) ParseMethodDecl() {
P.Trace("MethodDecl");
P.ParseIdent();
P.ParseParameters();
P.TryResult();
P.Optional(Scanner.SEMICOLON);
P.Ecart();
}
func (P *Parser) ParseInterfaceType() *Globals.Type {
P.Trace("InterfaceType");
P.Expect(Scanner.INTERFACE);
P.Expect(Scanner.LBRACE);
P.OpenScope();
typ := Globals.NewType(Type.INTERFACE);
typ.scope = P.top_scope;
for P.tok == Scanner.IDENT {
P.ParseMethodDecl();
}
P.CloseScope();
P.Expect(Scanner.RBRACE);
P.Ecart();
return typ;
}
func (P *Parser) ParseMapType() *Globals.Type {
P.Trace("MapType");
P.Expect(Scanner.MAP);
P.Expect(Scanner.LBRACK);
typ := Globals.NewType(Type.MAP);
typ.key = P.ParseType();
P.Expect(Scanner.RBRACK);
typ.elt = P.ParseType();
P.Ecart();
return typ;
}
func (P *Parser) ParseFieldDecl() {
P.Trace("FieldDecl");
P.ParseVarDeclList();
P.Ecart();
}
func (P *Parser) ParseStructType() *Globals.Type {
P.Trace("StructType");
P.Expect(Scanner.STRUCT);
P.Expect(Scanner.LBRACE);
P.OpenScope();
typ := Globals.NewType(Type.STRUCT);
typ.scope = P.top_scope;
for P.tok == Scanner.IDENT {
P.ParseFieldDecl();
if P.tok != Scanner.RBRACE {
P.Expect(Scanner.SEMICOLON);
}
}
P.Optional(Scanner.SEMICOLON);
P.CloseScope();
P.Expect(Scanner.RBRACE);
P.Ecart();
return typ;
}
func (P *Parser) ParsePointerType() *Globals.Type {
P.Trace("PointerType");
P.Expect(Scanner.MUL);
typ := Universe.undef_t;
if (EnableSemanticTests && P.tok == Scanner.IDENT && P.Lookup(P.val) == nil) {
// forward declaration
panic "UNIMPLEMENTED *forward_declared_type";
} else {
typ = Globals.NewType(Type.POINTER);
typ.elt = P.ParseType();
}
P.Ecart();
return typ;
}
// Returns nil if no type was found.
func (P *Parser) TryType() *Globals.Type {
P.Trace("Type (try)");
var typ *Globals.Type = nil;
switch P.tok {
case Scanner.IDENT: typ = P.ParseTypeName();
case Scanner.LBRACK: typ = P.ParseArrayType();
case Scanner.CHAN: typ = P.ParseChannelType();
case Scanner.INTERFACE: typ = P.ParseInterfaceType();
case Scanner.FUNC: typ = P.ParseFunctionType();
case Scanner.MAP: typ = P.ParseMapType();
case Scanner.STRUCT: typ = P.ParseStructType();
case Scanner.MUL: typ = P.ParsePointerType();
}
P.Ecart();
return typ;
}
// ----------------------------------------------------------------------------
// Blocks
func (P *Parser) ParseStatement() {
P.Trace("Statement");
if !P.TryStatement() {
P.Error(P.pos, "statement expected");
P.Next(); // make progress
}
P.Ecart();
}
func (P *Parser) ParseStatementList() {
P.Trace("StatementList");
for P.TryStatement() {
P.Optional(Scanner.SEMICOLON);
}
P.Ecart();
}
func (P *Parser) ParseBlock() {
P.Trace("Block");
P.Expect(Scanner.LBRACE);
P.OpenScope();
if P.tok != Scanner.RBRACE && P.tok != Scanner.SEMICOLON {
P.ParseStatementList();
}
P.Optional(Scanner.SEMICOLON);
P.CloseScope();
P.Expect(Scanner.RBRACE);
P.Ecart();
}
// ----------------------------------------------------------------------------
// Expressions
func (P *Parser) ParseExpressionList() *Globals.List {
P.Trace("ExpressionList");
list := Globals.NewList();
P.ParseExpression();
list.AddInt(0); // TODO fix this - add correct list element
for P.tok == Scanner.COMMA {
P.Next();
P.ParseExpression();
list.AddInt(0); // TODO fix this - add correct list element
}
P.Ecart();
return list;
}
func (P *Parser) ParseNew() {
P.Trace("New");
P.Expect(Scanner.NEW);
P.Expect(Scanner.LPAREN);
P.ParseType();
if P.tok == Scanner.COMMA {
P.Next();
P.ParseExpressionList()
}
P.Expect(Scanner.RPAREN);
P.Ecart();
}
func (P *Parser) ParseFunctionLit() {
P.Trace("FunctionLit");
P.ParseFunctionType();
P.ParseBlock();
P.Ecart();
}
func (P *Parser) ParseExpressionPair() {
P.Trace("ExpressionPair");
P.ParseExpression();
P.Expect(Scanner.COLON);
P.ParseExpression();
P.Ecart();
}
func (P *Parser) ParseExpressionPairList() {
P.Trace("ExpressionPairList");
P.ParseExpressionPair();
for (P.tok == Scanner.COMMA) {
P.ParseExpressionPair();
}
P.Ecart();
}
func (P *Parser) ParseBuiltinCall() {
P.Trace("BuiltinCall");
P.ParseExpressionList(); // TODO should be optional
P.Ecart();
}
func (P *Parser) ParseCompositeLit(typ *Globals.Type) {
P.Trace("CompositeLit");
// TODO I think we should use {} instead of () for
// composite literals to syntactically distinguish
// them from conversions. For now: allow both.
var paren int;
if P.tok == Scanner.LPAREN {
P.Next();
paren = Scanner.RPAREN;
} else {
P.Expect(Scanner.LBRACE);
paren = Scanner.RBRACE;
}
// TODO: should allow trailing ','
if P.tok != paren {
P.ParseExpression();
if P.tok == Scanner.COMMA {
P.Next();
if P.tok != paren {
P.ParseExpressionList();
}
} else if P.tok == Scanner.COLON {
P.Next();
P.ParseExpression();
if P.tok == Scanner.COMMA {
P.Next();
if P.tok != paren {
P.ParseExpressionPairList();
}
}
}
}
P.Expect(paren);
P.Ecart();
}
func (P *Parser) ParseOperand(pos int, ident string) {
P.Trace("Operand");
if pos < 0 && P.tok == Scanner.IDENT {
// no look-ahead yet
pos = P.pos;
ident = P.val;
P.Next();
}
if pos >= 0 {
// TODO set these up properly in the Universe
if ident == "panic" || ident == "print" {
P.ParseBuiltinCall();
goto exit;
}
P.ParseQualifiedIdent(pos, ident);
// TODO enable code below
/*
if obj.kind == Object.TYPE {
P.ParseCompositeLit(obj.typ);
}
*/
goto exit;
}
switch P.tok {
case Scanner.IDENT:
panic "UNREACHABLE";
case Scanner.LPAREN:
P.Next();
P.ParseExpression();
P.Expect(Scanner.RPAREN);
case Scanner.STRING: fallthrough;
case Scanner.NUMBER: fallthrough;
case Scanner.NIL: fallthrough;
case Scanner.IOTA: fallthrough;
case Scanner.TRUE: fallthrough;
case Scanner.FALSE:
P.Next();
case Scanner.FUNC:
P.ParseFunctionLit();
case Scanner.NEW:
P.ParseNew();
default:
typ := P.TryType();
if typ != nil {
P.ParseCompositeLit(typ);
} else {
P.Error(P.pos, "operand expected");
P.Next(); // make progress
}
}
exit:
P.Ecart();
}
func (P *Parser) ParseSelectorOrTypeAssertion() {
P.Trace("SelectorOrTypeAssertion");
P.Expect(Scanner.PERIOD);
if P.tok == Scanner.IDENT {
P.ParseIdent();
} else {
P.Expect(Scanner.LPAREN);
P.ParseType();
P.Expect(Scanner.RPAREN);
}
P.Ecart();
}
func (P *Parser) ParseIndexOrSlice() {
P.Trace("IndexOrSlice");
P.Expect(Scanner.LBRACK);
P.ParseExpression();
if P.tok == Scanner.COLON {
P.Next();
P.ParseExpression();
}
P.Expect(Scanner.RBRACK);
P.Ecart();
}
func (P *Parser) ParseCall() {
P.Trace("Call");
P.Expect(Scanner.LPAREN);
if P.tok != Scanner.RPAREN {
P.ParseExpressionList();
}
P.Expect(Scanner.RPAREN);
P.Ecart();
}
func (P *Parser) ParsePrimaryExpr(pos int, ident string) AST.Expr {
P.Trace("PrimaryExpr");
P.ParseOperand(pos, ident);
for {
switch P.tok {
case Scanner.PERIOD:
P.ParseSelectorOrTypeAssertion();
case Scanner.LBRACK:
P.ParseIndexOrSlice();
case Scanner.LPAREN:
P.ParseCall();
default:
P.Ecart();
return nil;
}
}
P.Ecart();
return nil;
}
func (P *Parser) ParsePrimaryExprList() {
P.Trace("PrimaryExprList");
P.ParsePrimaryExpr(-1, "");
for P.tok == Scanner.COMMA {
P.Next();
P.ParsePrimaryExpr(-1, "");
}
P.Ecart();
}
func (P *Parser) ParseUnaryExpr() AST.Expr {
P.Trace("UnaryExpr");
switch P.tok {
case Scanner.ADD: fallthrough;
case Scanner.SUB: fallthrough;
case Scanner.NOT: fallthrough;
case Scanner.XOR: fallthrough;
case Scanner.MUL: fallthrough;
case Scanner.RECV: fallthrough;
case Scanner.AND:
P.Next();
P.ParseUnaryExpr();
P.Ecart();
return nil; // TODO fix this
}
P.ParsePrimaryExpr(-1, "");
P.Ecart();
return nil; // TODO fix this
}
func Precedence(tok int) int {
// TODO should use a map or array here for lookup
switch tok {
case Scanner.LOR:
return 1;
case Scanner.LAND:
return 2;
case Scanner.SEND, Scanner.RECV:
return 3;
case Scanner.EQL, Scanner.NEQ, Scanner.LSS, Scanner.LEQ, Scanner.GTR, Scanner.GEQ:
return 4;
case Scanner.ADD, Scanner.SUB, Scanner.OR, Scanner.XOR:
return 5;
case Scanner.MUL, Scanner.QUO, Scanner.REM, Scanner.SHL, Scanner.SHR, Scanner.AND:
return 6;
}
return 0;
}
func (P *Parser) ParseBinaryExpr(pos int, ident string, prec1 int) AST.Expr {
P.Trace("BinaryExpr");
var x AST.Expr;
if pos >= 0 {
x = P.ParsePrimaryExpr(pos, ident);
} else {
x = P.ParseUnaryExpr();
}
for prec := Precedence(P.tok); prec >= prec1; prec-- {
for Precedence(P.tok) == prec {
e := new(AST.BinaryExpr);
e.typ = Universe.undef_t; // TODO fix this
e.op = P.tok; // TODO should we use tokens or separate operator constants?
e.x = x;
P.Next();
e.y = P.ParseBinaryExpr(-1, "", prec + 1);
x = e;
}
}
P.Ecart();
}
// Expressions where the first token may be an identifier which has already
// been consumed. If the identifier is present, pos is the identifier position,
// otherwise pos must be < 0 (and ident is ignored).
func (P *Parser) ParseIdentExpression(pos int, ident string) {
P.Trace("IdentExpression");
indent := P.indent;
P.ParseBinaryExpr(pos, ident, 1);
if indent != P.indent {
panic "imbalanced tracing code (Expression)";
}
P.Ecart();
}
func (P *Parser) ParseExpression() {
P.Trace("Expression");
P.ParseIdentExpression(-1, "");
P.Ecart();
}
// ----------------------------------------------------------------------------
// Statements
func (P *Parser) ConvertToExprList(pos_list, ident_list, expr_list *Globals.List) {
for p, q := pos_list.first, ident_list.first; q != nil; p, q = p.next, q.next {
pos, ident := p.val, q.str;
if EnableSemanticTests {
obj := P.Lookup(ident);
if obj == nil {
P.Error(pos, `"` + ident + `" is not declared`);
obj = Globals.NewObject(pos, Object.BAD, ident);
}
}
expr_list.AddInt(0); // TODO fix this - add correct expression
}
ident_list.Clear();
}
func (P *Parser) ParseIdentOrExpr(pos_list, ident_list, expr_list *Globals.List) {
P.Trace("IdentOrExpr");
pos_list.AddInt(P.pos);
pos, ident := -1, "";
just_ident := false;
if expr_list.len_ == 0 /* only idents so far */ && P.tok == Scanner.IDENT {
pos, ident = P.pos, P.val;
P.Next();
switch P.tok {
case Scanner.COMMA,
Scanner.COLON,
Scanner.DEFINE,
Scanner.ASSIGN,
Scanner.ADD_ASSIGN,
Scanner.SUB_ASSIGN,
Scanner.MUL_ASSIGN,
Scanner.QUO_ASSIGN,
Scanner.REM_ASSIGN,
Scanner.AND_ASSIGN,
Scanner.OR_ASSIGN,
Scanner.XOR_ASSIGN,
Scanner.SHL_ASSIGN,
Scanner.SHR_ASSIGN:
// identifier is not part of a more complicated expression
just_ident = true;
}
}
if just_ident {
ident_list.AddStr(ident);
} else {
P.ConvertToExprList(pos_list, ident_list, expr_list);
P.ParseIdentExpression(pos, ident);
expr_list.AddInt(0); // TODO fix this - add correct expression
}
P.Ecart();
}
func (P *Parser) ParseIdentOrExprList() (pos_list, ident_list, expr_list *Globals.List) {
P.Trace("IdentOrExprList");
pos_list, ident_list, expr_list = Globals.NewList(), Globals.NewList(), Globals.NewList();
P.ParseIdentOrExpr(pos_list, ident_list, expr_list);
for P.tok == Scanner.COMMA {
P.Next();
P.ParseIdentOrExpr(pos_list, ident_list, expr_list);
}
P.Ecart();
return pos_list, ident_list, expr_list;
}
func (P *Parser) ParseSimpleStat() {
P.Trace("SimpleStat");
// If we see an identifier, we don't know if it's part of a
// label declaration, (multiple) variable declaration, assignment,
// or simply an expression, without looking ahead.
// Strategy: We parse an expression list, but simultaneously, as
// long as possible, maintain a list of identifiers which is converted
// into an expression list only if neccessary. The result of
// ParseIdentOrExprList is a list of ident/expr positions and either
// a non-empty list of identifiers or a non-empty list of expressions
// (but not both).
pos_list, ident_list, expr_list := P.ParseIdentOrExprList();
switch P.tok {
case Scanner.COLON:
// label declaration
if EnableSemanticTests && ident_list.len_ != 1 {
P.Error(P.pos, "illegal label declaration");
}
P.Next();
case Scanner.DEFINE:
// variable declaration
if EnableSemanticTests && ident_list.len_ == 0 {
P.Error(P.pos, "illegal left-hand side for declaration");
}
P.Next();
pos := P.pos;
val_list := P.ParseExpressionList();
if EnableSemanticTests && val_list.len_ != ident_list.len_ {
P.Error(pos, "number of expressions does not match number of variables");
}
// declare variables
if EnableSemanticTests {
for p, q := pos_list.first, ident_list.first; q != nil; p, q = p.next, q.next {
obj := Globals.NewObject(p.val, Object.VAR, q.str);
P.Declare(obj);
// TODO set correct types
}
}
case Scanner.ASSIGN: fallthrough;
case Scanner.ADD_ASSIGN: fallthrough;
case Scanner.SUB_ASSIGN: fallthrough;
case Scanner.MUL_ASSIGN: fallthrough;
case Scanner.QUO_ASSIGN: fallthrough;
case Scanner.REM_ASSIGN: fallthrough;
case Scanner.AND_ASSIGN: fallthrough;
case Scanner.OR_ASSIGN: fallthrough;
case Scanner.XOR_ASSIGN: fallthrough;
case Scanner.SHL_ASSIGN: fallthrough;
case Scanner.SHR_ASSIGN:
P.ConvertToExprList(pos_list, ident_list, expr_list);
P.Next();
pos := P.pos;
val_list := P.ParseExpressionList();
if EnableSemanticTests && val_list.len_ != expr_list.len_ {
P.Error(pos, "number of expressions does not match number of variables");
}
default:
P.ConvertToExprList(pos_list, ident_list, expr_list);
if EnableSemanticTests && expr_list.len_ != 1 {
P.Error(P.pos, "no expression list allowed");
}
if P.tok == Scanner.INC || P.tok == Scanner.DEC {
P.Next();
}
}
P.Ecart();
}
func (P *Parser) ParseGoStat() {
P.Trace("GoStat");
P.Expect(Scanner.GO);
P.ParseExpression();
P.Ecart();
}
func (P *Parser) ParseReturnStat() {
P.Trace("ReturnStat");
P.Expect(Scanner.RETURN);
if P.tok != Scanner.SEMICOLON && P.tok != Scanner.RBRACE {
P.ParseExpressionList();
}
P.Ecart();
}
func (P *Parser) ParseControlFlowStat(tok int) {
P.Trace("ControlFlowStat");
P.Expect(tok);
if P.tok == Scanner.IDENT {
P.ParseIdent();
}
P.Ecart();
}
func (P *Parser) ParseIfStat() *AST.IfStat {
P.Trace("IfStat");
P.Expect(Scanner.IF);
P.OpenScope();
if P.tok != Scanner.LBRACE {
if P.tok != Scanner.SEMICOLON {
P.ParseSimpleStat();
}
if P.tok == Scanner.SEMICOLON {
P.Next();
if P.tok != Scanner.LBRACE {
P.ParseExpression();
}
}
}
P.ParseBlock();
if P.tok == Scanner.ELSE {
P.Next();
if P.tok == Scanner.IF {
P.ParseIfStat();
} else {
// TODO should be P.ParseBlock()
P.ParseStatement();
}
}
P.CloseScope();
P.Ecart();
}
func (P *Parser) ParseForStat() {
P.Trace("ForStat");
P.Expect(Scanner.FOR);
P.OpenScope();
if P.tok != Scanner.LBRACE {
if P.tok != Scanner.SEMICOLON {
P.ParseSimpleStat();
}
if P.tok == Scanner.SEMICOLON {
P.Next();
if P.tok != Scanner.SEMICOLON {
P.ParseExpression();
}
P.Expect(Scanner.SEMICOLON);
if P.tok != Scanner.LBRACE {
P.ParseSimpleStat();
}
}
}
P.ParseBlock();
P.CloseScope();
P.Ecart();
}
func (P *Parser) ParseCase() {
P.Trace("Case");
if P.tok == Scanner.CASE {
P.Next();
P.ParseExpressionList();
} else {
P.Expect(Scanner.DEFAULT);
}
P.Expect(Scanner.COLON);
P.Ecart();
}
func (P *Parser) ParseCaseList() {
P.Trace("CaseList");
P.ParseCase();
for P.tok == Scanner.CASE || P.tok == Scanner.DEFAULT {
P.ParseCase();
}
P.Ecart();
}
func (P *Parser) ParseCaseClause() {
P.Trace("CaseClause");
P.ParseCaseList();
if P.tok != Scanner.FALLTHROUGH && P.tok != Scanner.RBRACE {
P.ParseStatementList();
P.Optional(Scanner.SEMICOLON);
}
if P.tok == Scanner.FALLTHROUGH {
P.Next();
P.Optional(Scanner.SEMICOLON);
}
P.Ecart();
}
func (P *Parser) ParseSwitchStat() {
P.Trace("SwitchStat");
P.Expect(Scanner.SWITCH);
P.OpenScope();
if P.tok != Scanner.LBRACE {
if P.tok != Scanner.SEMICOLON {
P.ParseSimpleStat();
}
if P.tok == Scanner.SEMICOLON {
P.Next();
if P.tok != Scanner.LBRACE {
P.ParseExpression();
}
}
}
P.Expect(Scanner.LBRACE);
for P.tok == Scanner.CASE || P.tok == Scanner.DEFAULT {
P.ParseCaseClause();
}
P.Expect(Scanner.RBRACE);
P.CloseScope();
P.Ecart();
}
func (P *Parser) ParseCommCase() {
P.Trace("CommCase");
if P.tok == Scanner.CASE {
P.Next();
if P.tok == Scanner.GTR {
// send
P.Next();
P.ParseExpression();
P.Expect(Scanner.EQL);
P.ParseExpression();
} else {
// receive
if P.tok != Scanner.LSS {
P.ParseIdent();
P.Expect(Scanner.ASSIGN);
}
P.Expect(Scanner.LSS);
P.ParseExpression();
}
} else {
P.Expect(Scanner.DEFAULT);
}
P.Expect(Scanner.COLON);
P.Ecart();
}
func (P *Parser) ParseCommClause() {
P.Trace("CommClause");
P.ParseCommCase();
if P.tok != Scanner.CASE && P.tok != Scanner.DEFAULT && P.tok != Scanner.RBRACE {
P.ParseStatementList();
P.Optional(Scanner.SEMICOLON);
}
P.Ecart();
}
func (P *Parser) ParseRangeStat() bool {
P.Trace("RangeStat");
P.Expect(Scanner.RANGE);
P.ParseIdentList();
P.Expect(Scanner.DEFINE);
P.ParseExpression();
P.ParseBlock();
P.Ecart();
}
func (P *Parser) ParseSelectStat() bool {
P.Trace("SelectStat");
P.Expect(Scanner.SELECT);
P.Expect(Scanner.LBRACE);
for P.tok != Scanner.RBRACE && P.tok != Scanner.EOF {
P.ParseCommClause();
}
P.Next();
P.Ecart();
}
func (P *Parser) TryStatement() bool {
P.Trace("Statement (try)");
indent := P.indent;
res := true;
switch P.tok {
case Scanner.CONST: fallthrough;
case Scanner.TYPE: fallthrough;
case Scanner.VAR:
P.ParseDeclaration();
case Scanner.FUNC:
// for now we do not allow local function declarations
fallthrough;
case Scanner.MUL, Scanner.SEND, Scanner.RECV, Scanner.IDENT:
P.ParseSimpleStat();
case Scanner.GO:
P.ParseGoStat();
case Scanner.RETURN:
P.ParseReturnStat();
case Scanner.BREAK, Scanner.CONTINUE, Scanner.GOTO:
P.ParseControlFlowStat(P.tok);
case Scanner.LBRACE:
P.ParseBlock();
case Scanner.IF:
P.ParseIfStat();
case Scanner.FOR:
P.ParseForStat();
case Scanner.SWITCH:
P.ParseSwitchStat();
case Scanner.RANGE:
P.ParseRangeStat();
case Scanner.SELECT:
P.ParseSelectStat();
default:
// no statement found
res = false;
}
if indent != P.indent {
panic "imbalanced tracing code (Statement)"
}
P.Ecart();
return res;
}
// ----------------------------------------------------------------------------
// Declarations
func (P *Parser) ParseImportSpec() {
P.Trace("ImportSpec");
if P.tok == Scanner.PERIOD {
P.Next();
} else if P.tok == Scanner.IDENT {
P.Next();
}
P.Expect(Scanner.STRING);
P.Ecart();
}
func (P *Parser) ParseImportDecl() {
P.Trace("ImportDecl");
P.Expect(Scanner.IMPORT);
if P.tok == Scanner.LPAREN {
P.Next();
for P.tok != Scanner.RPAREN && P.tok != Scanner.EOF {
P.ParseImportSpec();
P.Optional(Scanner.SEMICOLON); // TODO this seems wrong
}
P.Next();
} else {
P.ParseImportSpec();
}
P.Ecart();
}
func (P *Parser) ParseConstSpec(exported bool) {
P.Trace("ConstSpec");
list := P.ParseIdentDeclList(Object.CONST);
typ := P.TryType();
if typ != nil {
for p := list.first; p != nil; p = p.next {
p.obj.mark = exported;
p.obj.typ = typ; // TODO should use/have set_type()!
}
}
if P.tok == Scanner.ASSIGN {
P.Next();
P.ParseExpressionList();
}
P.Ecart();
}
func (P *Parser) ParseConstDecl(exported bool) {
P.Trace("ConstDecl");
P.Expect(Scanner.CONST);
if P.tok == Scanner.LPAREN {
P.Next();
for P.tok == Scanner.IDENT {
P.ParseConstSpec(exported);
if P.tok != Scanner.RPAREN {
P.Expect(Scanner.SEMICOLON);
}
}
P.Next();
} else {
P.ParseConstSpec(exported);
}
P.Ecart();
}
func (P *Parser) ParseTypeSpec(exported bool) {
P.Trace("TypeSpec");
pos := P.pos;
ident := P.ParseIdent();
obj := P.top_scope.Lookup(ident); // only lookup in top scope!
if obj != nil {
// ok if forward declared type
if obj.kind != Object.TYPE || obj.typ.form != Type.UNDEF {
// TODO use obj.pos to refer to decl pos in error msg!
P.Error(pos, `"` + ident + `" is declared already`);
}
} else {
obj = Globals.NewObject(pos, Object.TYPE, ident);
obj.mark = exported;
obj.typ = Universe.undef_t; // TODO fix this
P.top_scope.Insert(obj);
}
typ := P.TryType(); // no type if we have a forward decl
if typ != nil {
// TODO what about the name of incomplete types?
obj.typ = typ; // TODO should use/have set_typ()!
if typ.obj == nil {
typ.obj = obj; // primary type object
}
}
P.Ecart();
}
func (P *Parser) ParseTypeDecl(exported bool) {
P.Trace("TypeDecl");
P.Expect(Scanner.TYPE);
if P.tok == Scanner.LPAREN {
P.Next();
for P.tok == Scanner.IDENT {
P.ParseTypeSpec(exported);
if P.tok != Scanner.RPAREN {
P.Expect(Scanner.SEMICOLON);
}
}
P.Next();
} else {
P.ParseTypeSpec(exported);
}
P.Ecart();
}
func (P *Parser) ParseVarSpec(exported bool) {
P.Trace("VarSpec");
list := P.ParseIdentDeclList(Object.VAR);
if P.tok == Scanner.ASSIGN {
P.Next();
P.ParseExpressionList();
} else {
typ := P.ParseType();
for p := list.first; p != nil; p = p.next {
p.obj.typ = typ; // TODO should use/have set_type()!
}
if P.tok == Scanner.ASSIGN {
P.Next();
P.ParseExpressionList();
}
}
P.Ecart();
}
func (P *Parser) ParseVarDecl(exported bool) {
P.Trace("VarDecl");
P.Expect(Scanner.VAR);
if P.tok == Scanner.LPAREN {
P.Next();
for P.tok == Scanner.IDENT {
P.ParseVarSpec(exported);
if P.tok != Scanner.RPAREN {
P.Expect(Scanner.SEMICOLON);
}
}
P.Next();
} else {
P.ParseVarSpec(exported);
}
P.Ecart();
}
func (P *Parser) ParseFuncDecl(exported bool) {
P.Trace("FuncDecl");
P.Expect(Scanner.FUNC);
P.ParseNamedSignature();
if P.tok == Scanner.SEMICOLON {
// forward declaration
P.Next();
} else {
P.ParseBlock();
}
P.Ecart();
}
func (P *Parser) ParseExportDecl() {
P.Trace("ExportDecl");
// TODO this needs to be clarified - the current syntax is
// "everything goes" - sigh...
//P.Expect(Scanner.EXPORT);
has_paren := false;
if P.tok == Scanner.LPAREN {
P.Next();
has_paren = true;
}
for P.tok == Scanner.IDENT {
P.exports.AddStr(P.ParseIdent());
P.Optional(Scanner.COMMA); // TODO this seems wrong
}
if has_paren {
P.Expect(Scanner.RPAREN)
}
P.Ecart();
}
func (P *Parser) ParseDeclaration() {
P.Trace("Declaration");
indent := P.indent;
exported := false;
if P.tok == Scanner.EXPORT {
P.Next();
exported = true;
}
switch P.tok {
case Scanner.CONST:
P.ParseConstDecl(exported);
case Scanner.TYPE:
P.ParseTypeDecl(exported);
case Scanner.VAR:
P.ParseVarDecl(exported);
case Scanner.FUNC:
P.ParseFuncDecl(exported);
case Scanner.EXPORT:
if exported {
P.Error(P.pos, "cannot mark export declaration for export");
}
P.Next();
P.ParseExportDecl();
default:
if exported && (P.tok == Scanner.IDENT || P.tok == Scanner.LPAREN) {
P.ParseExportDecl();
} else {
P.Error(P.pos, "declaration expected");
P.Next(); // make progress
}
}
if indent != P.indent {
panic "imbalanced tracing code (Declaration)"
}
P.Ecart();
}
// ----------------------------------------------------------------------------
// Program
func (P *Parser) MarkExports() {
if !EnableSemanticTests {
return;
}
scope := P.top_scope;
for p := P.exports.first; p != nil; p = p.next {
obj := scope.Lookup(p.str);
if obj != nil {
obj.mark = true;
// For now we export deep
// TODO this should change eventually - we need selective export
if obj.kind == Object.TYPE {
typ := obj.typ;
if typ.form == Type.STRUCT || typ.form == Type.INTERFACE {
scope := typ.scope;
for p := scope.entries.first; p != nil; p = p.next {
p.obj.mark = true;
}
}
}
} else {
// TODO need to report proper src position
P.Error(0, `"` + p.str + `" is not declared - cannot be exported`);
}
}
}
func (P *Parser) ParseProgram() {
P.Trace("Program");
P.OpenScope();
P.Expect(Scanner.PACKAGE);
pkg := P.comp.pkgs[0];
pkg.obj = P.ParseIdentDecl(Object.PACKAGE);
P.Optional(Scanner.SEMICOLON);
{ P.OpenScope();
pkg.scope = P.top_scope;
for P.tok == Scanner.IMPORT {
P.ParseImportDecl();
P.Optional(Scanner.SEMICOLON);
}
for P.tok != Scanner.EOF {
P.ParseDeclaration();
P.Optional(Scanner.SEMICOLON);
}
P.MarkExports();
P.CloseScope();
}
P.CloseScope();
P.Ecart();
}