mirror of
https://github.com/golang/go
synced 2024-11-26 14:08:37 -07:00
1070 lines
18 KiB
Go
1070 lines
18 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 Parser
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import Scanner "scanner"
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export Parser
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type Parser struct {
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verbose, indent int;
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S *Scanner.Scanner;
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tok int; // one token look-ahead
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beg, end int; // token position
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ident string; // last ident seen
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}
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func (P *Parser) PrintIndent() {
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for i := P.indent; i > 0; i-- {
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print ". ";
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}
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}
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func (P *Parser) Trace(msg string) {
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if P.verbose > 0 {
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P.PrintIndent();
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print msg, " {\n";
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P.indent++;
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}
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}
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func (P *Parser) Ecart() {
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if P.verbose > 0 {
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P.indent--;
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P.PrintIndent();
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print "}\n";
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}
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}
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func (P *Parser) Next() {
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P.tok, P.beg, P.end = P.S.Scan();
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if P.tok == Scanner.IDENT {
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P.ident = P.S.src[P.beg : P.end];
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}
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if P.verbose > 1 {
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P.PrintIndent();
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print Scanner.TokenName(P.tok), "\n";
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}
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}
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func (P *Parser) Open(S *Scanner.Scanner, verbose int) {
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P.verbose = verbose;
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P.indent = 0;
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P.S = S;
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P.Next();
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}
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func (P *Parser) Error(pos int, msg string) {
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P.S.Error(pos, msg);
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P.Next(); // make progress
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}
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func (P *Parser) Expect(tok int) {
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if P.tok == tok {
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P.Next()
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} else {
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P.Error(P.beg, "expected '" + Scanner.TokenName(tok) + "', found '" + Scanner.TokenName(P.tok) + "'");
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}
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}
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func (P *Parser) Optional(tok int) {
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if P.tok == tok {
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P.Next();
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}
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}
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func (P *Parser) TryType() bool;
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func (P *Parser) ParseExpression();
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func (P *Parser) ParseIdent() {
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if P.verbose > 0 {
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P.PrintIndent();
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print "Ident = \"", P.ident, "\"\n";
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}
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P.Expect(Scanner.IDENT);
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}
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func (P *Parser) ParseIdentList() {
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P.Trace("IdentList");
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P.ParseIdent();
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for P.tok == Scanner.COMMA {
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P.Next();
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P.ParseIdent();
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}
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P.Ecart();
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}
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func (P *Parser) ParseQualifiedIdent() {
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P.Trace("QualifiedIdent");
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P.ParseIdent();
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if P.tok == Scanner.PERIOD {
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P.Next();
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P.ParseIdent();
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}
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P.Ecart();
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}
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func (P *Parser) ParseTypeName() {
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P.Trace("TypeName");
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P.ParseQualifiedIdent();
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P.Ecart();
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}
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func (P *Parser) ParseType() {
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P.Trace("Type");
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if !P.TryType() {
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P.Error(P.beg, "type expected");
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}
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P.Ecart();
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}
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func (P *Parser) ParseArrayType() {
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P.Trace("ArrayType");
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P.Expect(Scanner.LBRACK);
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if P.tok != Scanner.RBRACK {
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P.ParseExpression();
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}
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P.Expect(Scanner.RBRACK);
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P.ParseType();
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P.Ecart();
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}
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func (P *Parser) ParseChannelType() {
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P.Trace("ChannelType");
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P.Expect(Scanner.CHAN);
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switch P.tok {
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case Scanner.LSS: fallthrough
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case Scanner.GTR:
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P.Next();
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}
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P.ParseType();
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P.Ecart();
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}
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func (P *Parser) ParseParameters();
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func (P *Parser) TryResult() bool;
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func (P *Parser) ParseMethodDecl() {
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P.Trace("MethodDecl");
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P.ParseIdent();
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P.ParseParameters();
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P.TryResult();
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P.Optional(Scanner.SEMICOLON);
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P.Ecart();
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}
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func (P *Parser) ParseInterfaceType() {
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P.Trace("InterfaceType");
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P.Expect(Scanner.INTERFACE);
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P.Expect(Scanner.LBRACE);
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for P.tok != Scanner.RBRACE {
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P.ParseMethodDecl();
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}
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P.Next();
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P.Ecart();
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}
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func (P *Parser) ParseAnonymousSignature();
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func (P *Parser) ParseFunctionType() {
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P.Trace("FunctionType");
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P.Expect(Scanner.FUNC);
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P.ParseAnonymousSignature();
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P.Ecart();
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}
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func (P *Parser) ParseMapType() {
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P.Trace("MapType");
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P.Expect(Scanner.MAP);
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P.Expect(Scanner.LBRACK);
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P.ParseType();
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P.Expect(Scanner.RBRACK);
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P.ParseType();
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P.Ecart();
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}
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func (P *Parser) ParseFieldDecl() {
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P.Trace("FieldDecl");
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P.ParseIdentList();
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P.ParseType();
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P.Ecart();
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}
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func (P *Parser) ParseStructType() {
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P.Trace("StructType");
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P.Expect(Scanner.STRUCT);
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P.Expect(Scanner.LBRACE);
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for P.tok != Scanner.RBRACE {
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P.ParseFieldDecl();
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if P.tok != Scanner.RBRACE {
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P.Expect(Scanner.SEMICOLON);
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}
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}
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P.Optional(Scanner.SEMICOLON);
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P.Expect(Scanner.RBRACE);
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P.Ecart();
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}
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func (P *Parser) ParsePointerType() {
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P.Trace("PointerType");
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P.Expect(Scanner.MUL);
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P.ParseType();
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P.Ecart();
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}
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func (P *Parser) TryType() bool {
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P.Trace("Type (try)");
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switch P.tok {
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case Scanner.IDENT:
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P.ParseTypeName();
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case Scanner.LBRACK:
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P.ParseArrayType();
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case Scanner.CHAN:
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P.ParseChannelType();
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case Scanner.INTERFACE:
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P.ParseInterfaceType();
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case Scanner.FUNC:
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P.ParseFunctionType();
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case Scanner.MAP:
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P.ParseMapType();
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case Scanner.STRUCT:
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P.ParseStructType();
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case Scanner.MUL:
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P.ParsePointerType();
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default:
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P.Ecart();
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return false;
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}
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P.Ecart();
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return true;
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}
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func (P *Parser) ParseImportSpec() {
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P.Trace("ImportSpec");
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if P.tok == Scanner.PERIOD {
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P.Next();
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} else if P.tok == Scanner.IDENT {
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P.Next();
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}
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P.Expect(Scanner.STRING);
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P.Ecart();
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}
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func (P *Parser) ParseImportDecl() {
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P.Trace("ImportDecl");
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P.Expect(Scanner.IMPORT);
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if P.tok == Scanner.LPAREN {
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P.Next();
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for P.tok != Scanner.RPAREN {
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P.ParseImportSpec();
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P.Optional(Scanner.SEMICOLON); // TODO this seems wrong
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}
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P.Next();
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} else {
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P.ParseImportSpec();
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}
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P.Ecart();
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}
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func (P *Parser) ParseExpressionList() {
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P.Trace("ExpressionList");
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P.ParseExpression();
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for P.tok == Scanner.COMMA {
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P.Next();
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P.ParseExpression();
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}
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P.Ecart();
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}
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func (P *Parser) ParseConstSpec() {
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P.Trace("ConstSpec");
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P.ParseIdent();
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P.TryType();
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if P.tok == Scanner.ASSIGN {
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P.Next();
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P.ParseExpression();
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}
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P.Ecart();
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}
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func (P *Parser) ParseConstDecl() {
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P.Trace("ConstDecl");
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P.Expect(Scanner.CONST);
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if P.tok == Scanner.LPAREN {
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P.Next();
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for P.tok != Scanner.RPAREN {
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P.ParseConstSpec();
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if P.tok != Scanner.RPAREN {
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P.Expect(Scanner.SEMICOLON);
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}
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}
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P.Next();
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} else {
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P.ParseConstSpec();
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}
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P.Ecart();
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}
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func (P *Parser) ParseTypeSpec() {
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P.Trace("TypeSpec");
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P.ParseIdent();
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P.TryType();
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P.Ecart();
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}
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func (P *Parser) ParseTypeDecl() {
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P.Trace("TypeDecl");
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P.Expect(Scanner.TYPE);
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if P.tok == Scanner.LPAREN {
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P.Next();
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for P.tok != Scanner.RPAREN {
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P.ParseTypeSpec();
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if P.tok != Scanner.RPAREN {
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P.Expect(Scanner.SEMICOLON);
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}
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}
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P.Next();
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} else {
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P.ParseTypeSpec();
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}
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P.Ecart();
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}
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func (P *Parser) ParseVarSpec() {
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P.Trace("VarSpec");
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P.ParseIdentList();
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if P.tok == Scanner.ASSIGN {
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P.Next();
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P.ParseExpressionList();
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} else {
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P.ParseType();
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if P.tok == Scanner.ASSIGN {
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P.Next();
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P.ParseExpressionList();
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}
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}
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P.Ecart();
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}
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func (P *Parser) ParseVarDecl() {
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P.Trace("VarDecl");
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P.Expect(Scanner.VAR);
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if P.tok == Scanner.LPAREN {
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P.Next();
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for P.tok != Scanner.RPAREN {
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P.ParseVarSpec();
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if P.tok != Scanner.RPAREN {
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P.Expect(Scanner.SEMICOLON);
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}
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}
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P.Next();
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} else {
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P.ParseVarSpec();
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}
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P.Ecart();
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}
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func (P *Parser) ParseParameterSection() {
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P.Trace("ParameterSection");
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P.ParseIdentList();
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P.ParseType();
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P.Ecart();
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}
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func (P *Parser) ParseParameterList() {
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P.Trace("ParameterList");
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P.ParseParameterSection();
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for P.tok == Scanner.COMMA {
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P.Next();
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P.ParseParameterSection();
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}
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P.Ecart();
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}
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func (P *Parser) ParseParameters() {
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P.Trace("Parameters");
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P.Expect(Scanner.LPAREN);
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if P.tok != Scanner.RPAREN {
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P.ParseParameterList();
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}
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P.Expect(Scanner.RPAREN);
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P.Ecart();
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}
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func (P *Parser) TryResult() bool {
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P.Trace("Result (try)");
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res := false;
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if P.tok == Scanner.LPAREN {
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// TODO: here we allow empty returns - should proably fix this
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P.ParseParameters();
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res = true;
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} else {
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res = P.TryType();
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}
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P.Ecart();
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return res;
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}
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// Anonymous signatures
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//
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// (params)
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// (params) type
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// (params) (results)
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// (recv) . (params)
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// (recv) . (params) type
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// (recv) . (params) (results)
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func (P *Parser) ParseAnonymousSignature() {
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P.Trace("AnonymousSignature");
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P.ParseParameters();
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if P.tok == Scanner.PERIOD {
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P.Next();
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P.ParseParameters();
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}
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P.TryResult();
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P.Ecart();
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}
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// Named signatures
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//
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// name (params)
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// name (params) type
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// name (params) (results)
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// (recv) name (params)
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// (recv) name (params) type
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// (recv) name (params) (results)
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func (P *Parser) ParseNamedSignature() {
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P.Trace("NamedSignature");
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if P.tok == Scanner.LPAREN {
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P.ParseParameters();
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}
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P.ParseIdent(); // function name
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P.ParseParameters();
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P.TryResult();
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P.Ecart();
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}
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func (P *Parser) ParseDeclaration();
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func (P *Parser) TryStatement() bool;
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func (P *Parser) ParseStatementList();
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func (P *Parser) ParseBlock();
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func (P *Parser) ParsePrimaryExpr();
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func (P *Parser) ParsePrimaryExprList() {
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P.Trace("PrimaryExprList");
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P.ParsePrimaryExpr();
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for P.tok == Scanner.COMMA {
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P.Next();
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P.ParsePrimaryExpr();
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}
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P.Ecart();
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}
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func (P *Parser) ParseBuiltinStat() {
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P.Trace("BuiltinStat");
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P.Expect(Scanner.IDENT);
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P.ParseExpressionList(); // TODO should be optional
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P.Ecart();
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}
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func (P *Parser) ParseSimpleStat() {
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P.Trace("SimpleStat");
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P.ParseExpression();
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if P.tok == Scanner.COLON {
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P.Next();
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P.Ecart();
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return;
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}
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if P.tok == Scanner.COMMA {
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P.Next();
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P.ParsePrimaryExprList();
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}
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switch P.tok {
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case Scanner.ASSIGN: fallthrough;
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case Scanner.DEFINE: fallthrough;
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case Scanner.ADD_ASSIGN: fallthrough;
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case Scanner.SUB_ASSIGN: fallthrough;
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case Scanner.MUL_ASSIGN: fallthrough;
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case Scanner.QUO_ASSIGN: fallthrough;
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case Scanner.REM_ASSIGN: fallthrough;
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case Scanner.AND_ASSIGN: fallthrough;
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case Scanner.OR_ASSIGN: fallthrough;
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case Scanner.XOR_ASSIGN: fallthrough;
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case Scanner.SHL_ASSIGN: fallthrough;
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case Scanner.SHR_ASSIGN:
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P.Next();
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P.ParseExpressionList();
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case Scanner.INC:
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P.Next();
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case Scanner.DEC:
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P.Next();
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}
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P.Ecart();
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}
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func (P *Parser) ParseGoStat() {
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P.Trace("GoStat");
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P.Expect(Scanner.GO);
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P.ParseExpression();
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P.Ecart();
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}
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func (P *Parser) ParseReturnStat() {
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P.Trace("ReturnStat");
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P.Expect(Scanner.RETURN);
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if P.tok != Scanner.SEMICOLON && P.tok != Scanner.RBRACE {
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P.ParseExpressionList();
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}
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P.Ecart();
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}
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func (P *Parser) ParseControlFlowStat(tok int) {
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P.Trace("ControlFlowStat");
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P.Expect(tok);
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if P.tok == Scanner.IDENT {
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P.ParseIdent();
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}
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P.Ecart();
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}
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func (P *Parser) ParseStatement() {
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P.Trace("Statement");
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if !P.TryStatement() {
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P.Error(P.beg, "statement expected");
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}
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P.Ecart();
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}
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func (P *Parser) ParseIfStat() {
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P.Trace("IfStat");
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P.Expect(Scanner.IF);
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if P.tok != Scanner.LBRACE {
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if P.tok != Scanner.SEMICOLON {
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P.ParseSimpleStat();
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}
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if P.tok == Scanner.SEMICOLON {
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P.Next();
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if P.tok != Scanner.LBRACE {
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P.ParseExpression();
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}
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}
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}
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P.ParseBlock();
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if P.tok == Scanner.ELSE {
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P.Next();
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if P.tok == Scanner.IF {
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P.ParseIfStat();
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} else {
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// TODO should be P.ParseBlock()
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P.ParseStatement();
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}
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}
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P.Ecart();
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}
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func (P *Parser) ParseForStat() {
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P.Trace("ForStat");
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P.Expect(Scanner.FOR);
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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.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);
|
|
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.RBRACE {
|
|
P.ParseCaseClause();
|
|
}
|
|
P.Expect(Scanner.RBRACE);
|
|
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.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: fallthrough;
|
|
case Scanner.FUNC:
|
|
P.ParseDeclaration();
|
|
case Scanner.GTR:
|
|
P.ParseSimpleStat(); // send
|
|
case Scanner.IDENT:
|
|
switch P.ident {
|
|
case "print", "panic":
|
|
P.ParseBuiltinStat();
|
|
default:
|
|
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"
|
|
}
|
|
P.Ecart();
|
|
return res;
|
|
}
|
|
|
|
|
|
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);
|
|
if P.tok != Scanner.RBRACE && P.tok != Scanner.SEMICOLON {
|
|
P.ParseStatementList();
|
|
}
|
|
P.Optional(Scanner.SEMICOLON);
|
|
P.Expect(Scanner.RBRACE);
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
func (P *Parser) ParseFuncDecl() {
|
|
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");
|
|
P.Expect(Scanner.EXPORT);
|
|
if P.tok == Scanner.LPAREN {
|
|
P.Next();
|
|
for P.tok != Scanner.RPAREN {
|
|
P.ParseIdent();
|
|
P.Optional(Scanner.COMMA); // TODO this seems wrong
|
|
}
|
|
P.Next();
|
|
} else {
|
|
P.ParseIdent();
|
|
for P.tok == Scanner.COMMA {
|
|
P.Next();
|
|
P.ParseIdent();
|
|
}
|
|
}
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
func (P *Parser) ParseDeclaration() {
|
|
P.Trace("Declaration");
|
|
indent := P.indent;
|
|
switch P.tok {
|
|
case Scanner.CONST:
|
|
P.ParseConstDecl();
|
|
case Scanner.TYPE:
|
|
P.ParseTypeDecl();
|
|
case Scanner.VAR:
|
|
P.ParseVarDecl();
|
|
case Scanner.FUNC:
|
|
P.ParseFuncDecl();
|
|
case Scanner.EXPORT:
|
|
P.ParseExportDecl();
|
|
default:
|
|
P.Error(P.beg, "declaration expected");
|
|
}
|
|
if indent != P.indent {
|
|
panic "imbalanced tracing code"
|
|
}
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
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) ParseOperand() {
|
|
P.Trace("Operand");
|
|
switch P.tok {
|
|
case Scanner.IDENT:
|
|
P.ParseQualifiedIdent();
|
|
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.NEW:
|
|
P.ParseNew();
|
|
default:
|
|
P.Error(P.beg, "operand expected");
|
|
}
|
|
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) ParseInvocation() {
|
|
P.Trace("Invocation");
|
|
P.Expect(Scanner.LPAREN);
|
|
if P.tok != Scanner.RPAREN {
|
|
P.ParseExpressionList();
|
|
}
|
|
P.Expect(Scanner.RPAREN);
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
func (P *Parser) ParsePrimaryExpr() {
|
|
P.Trace("PrimaryExpr");
|
|
P.ParseOperand();
|
|
for {
|
|
switch P.tok {
|
|
case Scanner.PERIOD:
|
|
P.ParseSelectorOrTypeAssertion();
|
|
case Scanner.LBRACK:
|
|
P.ParseIndexOrSlice();
|
|
case Scanner.LPAREN:
|
|
P.ParseInvocation();
|
|
default:
|
|
P.Ecart();
|
|
return;
|
|
}
|
|
}
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
func (P *Parser) ParseUnaryExpr() {
|
|
P.Trace("UnaryExpr");
|
|
switch P.tok {
|
|
case Scanner.ADD: fallthrough;
|
|
case Scanner.SUB: fallthrough;
|
|
case Scanner.NOT: fallthrough;
|
|
case Scanner.XOR: fallthrough;
|
|
case Scanner.LSS: fallthrough;
|
|
case Scanner.GTR: fallthrough;
|
|
case Scanner.MUL: fallthrough;
|
|
case Scanner.AND:
|
|
P.Next();
|
|
P.ParseUnaryExpr();
|
|
P.Ecart();
|
|
return;
|
|
}
|
|
P.ParsePrimaryExpr();
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
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.EQL, Scanner.NEQ, Scanner.LSS, Scanner.LEQ, Scanner.GTR, Scanner.GEQ:
|
|
return 3;
|
|
case Scanner.ADD, Scanner.SUB, Scanner.OR, Scanner.XOR:
|
|
return 4;
|
|
case Scanner.MUL, Scanner.QUO, Scanner.REM, Scanner.SHL, Scanner.SHR, Scanner.AND:
|
|
return 5;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
func (P *Parser) ParseBinaryExpr(prec1 int) {
|
|
P.Trace("BinaryExpr");
|
|
P.ParseUnaryExpr();
|
|
for prec := Precedence(P.tok); prec >= prec1; prec-- {
|
|
for Precedence(P.tok) == prec {
|
|
P.Next();
|
|
P.ParseBinaryExpr(prec + 1);
|
|
}
|
|
}
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
func (P *Parser) ParseExpression() {
|
|
P.Trace("Expression");
|
|
indent := P.indent;
|
|
P.ParseBinaryExpr(1);
|
|
if indent != P.indent {
|
|
panic "imbalanced tracing code";
|
|
}
|
|
P.Ecart();
|
|
}
|
|
|
|
|
|
func (P *Parser) ParseProgram() {
|
|
P.Trace("Program");
|
|
P.Expect(Scanner.PACKAGE);
|
|
P.ParseIdent();
|
|
P.Optional(Scanner.SEMICOLON);
|
|
|
|
for P.tok == Scanner.IMPORT {
|
|
P.ParseImportDecl();
|
|
P.Optional(Scanner.SEMICOLON);
|
|
}
|
|
|
|
for P.tok != Scanner.EOF {
|
|
P.ParseDeclaration();
|
|
P.Optional(Scanner.SEMICOLON);
|
|
}
|
|
P.Ecart();
|
|
}
|