mirror of
https://github.com/golang/go
synced 2024-11-20 10:44:41 -07:00
775 lines
13 KiB
Go
775 lines
13 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 Scanner
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import "utf8"
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import Utils "utils"
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export const (
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ILLEGAL = iota;
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IDENT;
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INT;
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FLOAT;
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STRING;
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EOF;
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COMMENT;
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ADD;
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SUB;
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MUL;
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QUO;
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REM;
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AND;
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OR;
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XOR;
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SHL;
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SHR;
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ADD_ASSIGN;
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SUB_ASSIGN;
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MUL_ASSIGN;
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QUO_ASSIGN;
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REM_ASSIGN;
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AND_ASSIGN;
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OR_ASSIGN;
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XOR_ASSIGN;
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SHL_ASSIGN;
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SHR_ASSIGN;
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LAND;
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LOR;
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ARROW;
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INC;
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DEC;
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EQL;
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NEQ;
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LSS;
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LEQ;
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GTR;
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GEQ;
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ASSIGN;
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DEFINE;
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NOT;
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ELLIPSIS;
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LPAREN;
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RPAREN;
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LBRACK;
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RBRACK;
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LBRACE;
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RBRACE;
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COMMA;
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SEMICOLON;
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COLON;
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PERIOD;
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// keywords
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KEYWORDS_BEG;
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BREAK;
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CASE;
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CHAN;
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CONST;
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CONTINUE;
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DEFAULT;
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ELSE;
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EXPORT;
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FALLTHROUGH;
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FOR;
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FUNC;
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GO;
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GOTO;
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IF;
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IMPORT;
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INTERFACE;
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MAP;
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PACKAGE;
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RANGE;
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RETURN;
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SELECT;
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STRUCT;
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SWITCH;
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TYPE;
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VAR;
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KEYWORDS_END;
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// AST use only
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EXPRSTAT;
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)
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export func TokenString(tok int) string {
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switch tok {
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case ILLEGAL: return "ILLEGAL";
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case IDENT: return "IDENT";
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case INT: return "INT";
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case FLOAT: return "FLOAT";
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case STRING: return "STRING";
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case EOF: return "EOF";
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case COMMENT: return "COMMENT";
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case ADD: return "+";
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case SUB: return "-";
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case MUL: return "*";
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case QUO: return "/";
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case REM: return "%";
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case AND: return "&";
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case OR: return "|";
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case XOR: return "^";
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case SHL: return "<<";
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case SHR: return ">>";
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case ADD_ASSIGN: return "+=";
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case SUB_ASSIGN: return "-=";
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case MUL_ASSIGN: return "+=";
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case QUO_ASSIGN: return "/=";
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case REM_ASSIGN: return "%=";
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case AND_ASSIGN: return "&=";
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case OR_ASSIGN: return "|=";
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case XOR_ASSIGN: return "^=";
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case SHL_ASSIGN: return "<<=";
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case SHR_ASSIGN: return ">>=";
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case LAND: return "&&";
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case LOR: return "||";
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case ARROW: return "<-";
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case INC: return "++";
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case DEC: return "--";
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case EQL: return "==";
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case NEQ: return "!=";
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case LSS: return "<";
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case LEQ: return "<=";
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case GTR: return ">";
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case GEQ: return ">=";
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case ASSIGN: return "=";
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case DEFINE: return ":=";
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case NOT: return "!";
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case ELLIPSIS: return "...";
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case LPAREN: return "(";
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case RPAREN: return ")";
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case LBRACK: return "[";
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case RBRACK: return "]";
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case LBRACE: return "LBRACE";
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case RBRACE: return "RBRACE";
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case COMMA: return ",";
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case SEMICOLON: return ";";
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case COLON: return ":";
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case PERIOD: return ".";
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case BREAK: return "break";
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case CASE: return "case";
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case CHAN: return "chan";
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case CONST: return "const";
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case CONTINUE: return "continue";
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case DEFAULT: return "default";
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case ELSE: return "else";
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case EXPORT: return "export";
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case FALLTHROUGH: return "fallthrough";
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case FOR: return "for";
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case FUNC: return "func";
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case GO: return "go";
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case GOTO: return "goto";
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case IF: return "if";
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case IMPORT: return "import";
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case INTERFACE: return "interface";
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case MAP: return "map";
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case PACKAGE: return "package";
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case RANGE: return "range";
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case RETURN: return "return";
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case SELECT: return "select";
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case STRUCT: return "struct";
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case SWITCH: return "switch";
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case TYPE: return "type";
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case VAR: return "var";
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case EXPRSTAT: return "EXPRSTAT";
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}
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return "token(" + Utils.IntToString(tok, 10) + ")";
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}
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export const (
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LowestPrec = -1;
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UnaryPrec = 7;
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HighestPrec = 8;
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)
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export func Precedence(tok int) int {
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switch tok {
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case COLON:
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return 0;
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case LOR:
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return 1;
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case LAND:
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return 2;
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case ARROW:
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return 3;
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case EQL, NEQ, LSS, LEQ, GTR, GEQ:
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return 4;
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case ADD, SUB, OR, XOR:
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return 5;
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case MUL, QUO, REM, SHL, SHR, AND:
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return 6;
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}
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return LowestPrec;
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}
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var Keywords map [string] int;
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func init() {
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Keywords = make(map [string] int);
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for i := KEYWORDS_BEG + 1; i < KEYWORDS_END; i++ {
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Keywords[TokenString(i)] = i;
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}
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}
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func is_letter(ch int) bool {
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return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= 128 ;
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}
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func digit_val(ch int) int {
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if '0' <= ch && ch <= '9' {
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return ch - '0';
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}
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if 'a' <= ch && ch <= 'f' {
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return ch - 'a' + 10;
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}
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if 'A' <= ch && ch <= 'F' {
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return ch - 'A' + 10;
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}
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return 16; // larger than any legal digit val
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}
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export type ErrorHandler interface {
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Error(pos int, msg string);
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Warning(pos int, msg string);
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}
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export type Scanner struct {
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// setup
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err ErrorHandler;
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src string; // source
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scan_comments bool;
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// scanning
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pos int; // current reading position
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ch int; // one char look-ahead
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chpos int; // position of ch
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linepos int; // position of beginning of line
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// testmode
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testmode bool;
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testpos int;
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}
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// Read the next Unicode char into S.ch.
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// S.ch < 0 means end-of-file.
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func (S *Scanner) Next() {
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if S.pos < len(S.src) {
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// assume ascii
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r, w := int(S.src[S.pos]), 1;
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if r >= 0x80 {
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// not ascii
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r, w = utf8.DecodeRuneInString(S.src, S.pos);
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}
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S.ch = r;
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S.chpos = S.pos;
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S.pos += w;
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} else {
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S.ch = -1; // eof
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S.chpos = len(S.src);
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}
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}
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func (S *Scanner) Error(pos int, msg string) {
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// check for expected errors (test mode)
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if S.testpos < 0 || pos == S.testpos {
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// test mode:
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// S.testpos < 0: // follow-up errors are expected and ignored
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// S.testpos == 0: // an error is expected at S.testpos and ignored
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S.testpos = -1;
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return;
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}
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S.err.Error(pos, msg);
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}
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func (S *Scanner) ExpectNoErrors() {
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// set the next expected error position to one after eof
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// (the eof position is a legal error position!)
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S.testpos = len(S.src) + 1;
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}
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func (S *Scanner) Init(err ErrorHandler, src string, scan_comments, testmode bool) {
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S.err = err;
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S.src = src;
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S.scan_comments = scan_comments;
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S.pos = 0;
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S.linepos = 0;
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S.testmode = testmode;
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S.ExpectNoErrors(); // S.src must be set
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S.Next(); // S.ExpectNoErrrors() must be called before
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}
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func CharString(ch int) string {
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s := string(ch);
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switch ch {
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case '\a': s = `\a`;
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case '\b': s = `\b`;
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case '\f': s = `\f`;
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case '\n': s = `\n`;
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case '\r': s = `\r`;
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case '\t': s = `\t`;
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case '\v': s = `\v`;
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case '\\': s = `\\`;
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case '\'': s = `\'`;
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}
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return "'" + s + "' (U+" + Utils.IntToString(ch, 16) + ")";
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}
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func (S *Scanner) Expect(ch int) {
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if S.ch != ch {
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S.Error(S.chpos, "expected " + CharString(ch) + ", found " + CharString(S.ch));
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}
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S.Next(); // make always progress
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}
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func (S *Scanner) SkipWhitespace() {
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for {
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switch S.ch {
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case '\t', '\r', ' ':
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// nothing to do
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case '\n':
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if S.scan_comments {
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return;
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}
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default:
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return;
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}
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S.Next();
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}
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panic("UNREACHABLE");
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}
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func (S *Scanner) ScanComment() string {
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// first '/' already consumed
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pos := S.chpos - 1;
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if S.ch == '/' {
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//-style comment
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S.Next();
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for S.ch >= 0 {
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S.Next();
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if S.ch == '\n' {
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// '\n' terminates comment but we do not include
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// it in the comment (otherwise we don't see the
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// start of a newline in SkipWhitespace()).
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goto exit;
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}
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}
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} else {
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/*-style comment */
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S.Expect('*');
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for S.ch >= 0 {
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ch := S.ch;
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S.Next();
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if ch == '*' && S.ch == '/' {
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S.Next();
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goto exit;
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}
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}
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}
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S.Error(pos, "comment not terminated");
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exit:
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comment := S.src[pos : S.chpos];
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if S.testmode {
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// interpret ERROR and SYNC comments
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oldpos := -1;
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switch {
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case len(comment) >= 8 && comment[3 : 8] == "ERROR" :
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// an error is expected at the next token position
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oldpos = S.testpos;
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S.SkipWhitespace();
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S.testpos = S.chpos;
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case len(comment) >= 7 && comment[3 : 7] == "SYNC" :
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// scanning/parsing synchronized again - no (follow-up) errors expected
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oldpos = S.testpos;
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S.ExpectNoErrors();
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}
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if 0 <= oldpos && oldpos <= len(S.src) {
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// the previous error was not found
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S.Error(oldpos, "ERROR not found"); // TODO this should call ErrorMsg
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}
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}
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return comment;
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}
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func (S *Scanner) ScanIdentifier() (tok int, val string) {
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pos := S.chpos;
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for is_letter(S.ch) || digit_val(S.ch) < 10 {
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S.Next();
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}
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val = S.src[pos : S.chpos];
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var present bool;
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tok, present = Keywords[val];
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if !present {
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tok = IDENT;
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}
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return tok, val;
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}
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func (S *Scanner) ScanMantissa(base int) {
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for digit_val(S.ch) < base {
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S.Next();
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}
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}
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func (S *Scanner) ScanNumber(seen_decimal_point bool) (tok int, val string) {
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pos := S.chpos;
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tok = INT;
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if seen_decimal_point {
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tok = FLOAT;
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pos--; // '.' is one byte
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S.ScanMantissa(10);
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goto exponent;
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}
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if S.ch == '0' {
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// int or float
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S.Next();
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if S.ch == 'x' || S.ch == 'X' {
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// hexadecimal int
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S.Next();
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S.ScanMantissa(16);
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} else {
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// octal int or float
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S.ScanMantissa(8);
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if digit_val(S.ch) < 10 || S.ch == '.' || S.ch == 'e' || S.ch == 'E' {
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// float
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tok = FLOAT;
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goto mantissa;
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}
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// octal int
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}
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goto exit;
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}
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mantissa:
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// decimal int or float
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S.ScanMantissa(10);
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if S.ch == '.' {
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// float
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tok = FLOAT;
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S.Next();
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S.ScanMantissa(10)
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}
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exponent:
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if S.ch == 'e' || S.ch == 'E' {
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// float
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tok = FLOAT;
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S.Next();
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if S.ch == '-' || S.ch == '+' {
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S.Next();
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}
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S.ScanMantissa(10);
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}
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exit:
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return tok, S.src[pos : S.chpos];
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}
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func (S *Scanner) ScanDigits(n int, base int) {
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for digit_val(S.ch) < base {
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S.Next();
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n--;
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}
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if n > 0 {
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S.Error(S.chpos, "illegal char escape");
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}
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}
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func (S *Scanner) ScanEscape(quote int) string {
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// TODO: fix this routine
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ch := S.ch;
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pos := S.chpos;
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S.Next();
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switch ch {
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case 'a', 'b', 'f', 'n', 'r', 't', 'v', '\\':
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return string(ch);
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case '0', '1', '2', '3', '4', '5', '6', '7':
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S.ScanDigits(3 - 1, 8); // 1 char already read
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return ""; // TODO fix this
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case 'x':
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S.ScanDigits(2, 16);
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return ""; // TODO fix this
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case 'u':
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S.ScanDigits(4, 16);
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return ""; // TODO fix this
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case 'U':
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S.ScanDigits(8, 16);
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return ""; // TODO fix this
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default:
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// check for quote outside the switch for better generated code (eventually)
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if ch == quote {
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return string(quote);
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}
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S.Error(pos, "illegal char escape");
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}
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return ""; // TODO fix this
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}
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func (S *Scanner) ScanChar() string {
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// '\'' already consumed
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pos := S.chpos - 1;
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ch := S.ch;
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S.Next();
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if ch == '\\' {
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S.ScanEscape('\'');
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}
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S.Expect('\'');
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return S.src[pos : S.chpos];
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}
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func (S *Scanner) ScanString() string {
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// '"' already consumed
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pos := S.chpos - 1;
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for S.ch != '"' {
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ch := S.ch;
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S.Next();
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if ch == '\n' || ch < 0 {
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S.Error(pos, "string not terminated");
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break;
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}
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if ch == '\\' {
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S.ScanEscape('"');
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}
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}
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S.Next();
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return S.src[pos : S.chpos];
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}
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func (S *Scanner) ScanRawString() string {
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// '`' already consumed
|
|
|
|
pos := S.chpos - 1;
|
|
for S.ch != '`' {
|
|
ch := S.ch;
|
|
S.Next();
|
|
if ch == '\n' || ch < 0 {
|
|
S.Error(pos, "string not terminated");
|
|
break;
|
|
}
|
|
}
|
|
|
|
S.Next();
|
|
return S.src[pos : S.chpos];
|
|
}
|
|
|
|
|
|
func (S *Scanner) Select2(tok0, tok1 int) int {
|
|
if S.ch == '=' {
|
|
S.Next();
|
|
return tok1;
|
|
}
|
|
return tok0;
|
|
}
|
|
|
|
|
|
func (S *Scanner) Select3(tok0, tok1, ch2, tok2 int) int {
|
|
if S.ch == '=' {
|
|
S.Next();
|
|
return tok1;
|
|
}
|
|
if S.ch == ch2 {
|
|
S.Next();
|
|
return tok2;
|
|
}
|
|
return tok0;
|
|
}
|
|
|
|
|
|
func (S *Scanner) Select4(tok0, tok1, ch2, tok2, tok3 int) int {
|
|
if S.ch == '=' {
|
|
S.Next();
|
|
return tok1;
|
|
}
|
|
if S.ch == ch2 {
|
|
S.Next();
|
|
if S.ch == '=' {
|
|
S.Next();
|
|
return tok3;
|
|
}
|
|
return tok2;
|
|
}
|
|
return tok0;
|
|
}
|
|
|
|
|
|
func (S *Scanner) Scan() (pos, tok int, val string) {
|
|
L: S.SkipWhitespace();
|
|
|
|
pos, tok = S.chpos, ILLEGAL;
|
|
|
|
switch ch := S.ch; {
|
|
case is_letter(ch): tok, val = S.ScanIdentifier();
|
|
case digit_val(ch) < 10: tok, val = S.ScanNumber(false);
|
|
default:
|
|
S.Next(); // always make progress
|
|
switch ch {
|
|
case -1: tok = EOF;
|
|
case '\n': tok, val = COMMENT, "\n";
|
|
case '"': tok, val = STRING, S.ScanString();
|
|
case '\'': tok, val = INT, S.ScanChar();
|
|
case '`': tok, val = STRING, S.ScanRawString();
|
|
case ':': tok = S.Select2(COLON, DEFINE);
|
|
case '.':
|
|
if digit_val(S.ch) < 10 {
|
|
tok, val = S.ScanNumber(true);
|
|
} else if S.ch == '.' {
|
|
S.Next();
|
|
if S.ch == '.' {
|
|
S.Next();
|
|
tok = ELLIPSIS;
|
|
}
|
|
} else {
|
|
tok = PERIOD;
|
|
}
|
|
case ',': tok = COMMA;
|
|
case ';': tok = SEMICOLON;
|
|
case '(': tok = LPAREN;
|
|
case ')': tok = RPAREN;
|
|
case '[': tok = LBRACK;
|
|
case ']': tok = RBRACK;
|
|
case '{': tok = LBRACE;
|
|
case '}': tok = RBRACE;
|
|
case '+': tok = S.Select3(ADD, ADD_ASSIGN, '+', INC);
|
|
case '-': tok = S.Select3(SUB, SUB_ASSIGN, '-', DEC);
|
|
case '*': tok = S.Select2(MUL, MUL_ASSIGN);
|
|
case '/':
|
|
if S.ch == '/' || S.ch == '*' {
|
|
tok, val = COMMENT, S.ScanComment();
|
|
if !S.scan_comments {
|
|
goto L;
|
|
}
|
|
} else {
|
|
tok = S.Select2(QUO, QUO_ASSIGN);
|
|
}
|
|
case '%': tok = S.Select2(REM, REM_ASSIGN);
|
|
case '^': tok = S.Select2(XOR, XOR_ASSIGN);
|
|
case '<':
|
|
if S.ch == '-' {
|
|
S.Next();
|
|
tok = ARROW;
|
|
} else {
|
|
tok = S.Select4(LSS, LEQ, '<', SHL, SHL_ASSIGN);
|
|
}
|
|
case '>': tok = S.Select4(GTR, GEQ, '>', SHR, SHR_ASSIGN);
|
|
case '=': tok = S.Select2(ASSIGN, EQL);
|
|
case '!': tok = S.Select2(NOT, NEQ);
|
|
case '&': tok = S.Select3(AND, AND_ASSIGN, '&', LAND);
|
|
case '|': tok = S.Select3(OR, OR_ASSIGN, '|', LOR);
|
|
default:
|
|
S.Error(pos, "illegal character " + CharString(ch));
|
|
tok = ILLEGAL;
|
|
}
|
|
}
|
|
|
|
return pos, tok, val;
|
|
}
|
|
|
|
|
|
export type Token struct {
|
|
pos int;
|
|
tok int;
|
|
val string;
|
|
}
|
|
|
|
|
|
func (S *Scanner) TokenStream() <-chan *Token {
|
|
ch := make(chan *Token, 100);
|
|
go func(S *Scanner, ch chan <- *Token) {
|
|
for {
|
|
t := new(Token);
|
|
t.pos, t.tok, t.val = S.Scan();
|
|
ch <- t;
|
|
if t.tok == EOF {
|
|
break;
|
|
}
|
|
}
|
|
}(S, ch);
|
|
return ch;
|
|
}
|