summaryrefslogtreecommitdiff
path: root/src/lib/go/scanner/scanner.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/lib/go/scanner/scanner.go')
-rw-r--r--src/lib/go/scanner/scanner.go501
1 files changed, 0 insertions, 501 deletions
diff --git a/src/lib/go/scanner/scanner.go b/src/lib/go/scanner/scanner.go
deleted file mode 100644
index a90e6f259..000000000
--- a/src/lib/go/scanner/scanner.go
+++ /dev/null
@@ -1,501 +0,0 @@
-// 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.
-
-// A scanner for Go source text. Takes a []byte as source which can
-// then be tokenized through repeated calls to the Scan function.
-// For a sample use of a scanner, see the implementation of Tokenize.
-//
-package scanner
-
-import (
- "go/token";
- "strconv";
- "unicode";
- "utf8";
-)
-
-
-// An implementation of an ErrorHandler may be provided to the Scanner.
-// If a syntax error is encountered and a handler was installed, Error
-// is called with a position and an error message. The position points
-// to the beginning of the offending token.
-//
-type ErrorHandler interface {
- Error(pos token.Position, msg string);
-}
-
-
-// A Scanner holds the scanner's internal state while processing
-// a given text. It can be allocated as part of another data
-// structure but must be initialized via Init before use. For
-// a sample use, see the implementation of Tokenize.
-//
-type Scanner struct {
- // immutable state
- src []byte; // source
- err ErrorHandler; // error reporting; or nil
- mode uint; // scanning mode
-
- // scanning state
- pos token.Position; // previous reading position (position before ch)
- offset int; // current reading offset (position after ch)
- ch int; // one char look-ahead
-
- // public state - ok to modify
- ErrorCount int; // number of errors encountered
-}
-
-
-// Read the next Unicode char into S.ch.
-// S.ch < 0 means end-of-file.
-//
-func (S *Scanner) next() {
- if S.offset < len(S.src) {
- S.pos.Offset = S.offset;
- S.pos.Column++;
- r, w := int(S.src[S.offset]), 1;
- switch {
- case r == '\n':
- S.pos.Line++;
- S.pos.Column = 0;
- case r >= 0x80:
- // not ASCII
- r, w = utf8.DecodeRune(S.src[S.offset : len(S.src)]);
- }
- S.offset += w;
- S.ch = r;
- } else {
- S.pos.Offset = len(S.src);
- S.ch = -1; // eof
- }
-}
-
-
-// The mode parameter to the Init function is a set of flags (or 0).
-// They control scanner behavior.
-//
-const (
- ScanComments = 1 << iota; // return comments as COMMENT tokens
- AllowIllegalChars; // do not report an error for illegal chars
-)
-
-
-// Init prepares the scanner S to tokenize the text src. Calls to Scan
-// will use the error handler err if they encounter a syntax error and
-// err is not nil. Also, for each error encountered, the Scanner field
-// ErrorCount is incremented by one. The mode parameter determines how
-// comments and illegal characters are handled.
-//
-func (S *Scanner) Init(src []byte, err ErrorHandler, mode uint) {
- // Explicitly initialize all fields since a scanner may be reused.
- S.src = src;
- S.err = err;
- S.mode = mode;
- S.pos = token.Position{0, 1, 0};
- S.offset = 0;
- S.ErrorCount = 0;
- S.next();
-}
-
-
-func charString(ch int) string {
- var s string;
- switch ch {
- case '\a': s = `\a`;
- case '\b': s = `\b`;
- case '\f': s = `\f`;
- case '\n': s = `\n`;
- case '\r': s = `\r`;
- case '\t': s = `\t`;
- case '\v': s = `\v`;
- case '\\': s = `\\`;
- case '\'': s = `\'`;
- default : s = string(ch);
- }
- return "'" + s + "' (U+" + strconv.Itob(ch, 16) + ")";
-}
-
-
-func (S *Scanner) error(pos token.Position, msg string) {
- if S.err != nil {
- S.err.Error(pos, msg);
- }
- S.ErrorCount++;
-}
-
-
-func (S *Scanner) expect(ch int) {
- if S.ch != ch {
- S.error(S.pos, "expected " + charString(ch) + ", found " + charString(S.ch));
- }
- S.next(); // always make progress
-}
-
-
-func (S *Scanner) scanComment(pos token.Position) {
- // first '/' already consumed
-
- if S.ch == '/' {
- //-style comment
- for S.ch >= 0 {
- S.next();
- if S.ch == '\n' {
- S.next(); // '\n' belongs to the comment
- return;
- }
- }
-
- } else {
- /*-style comment */
- S.expect('*');
- for S.ch >= 0 {
- ch := S.ch;
- S.next();
- if ch == '*' && S.ch == '/' {
- S.next();
- return;
- }
- }
- }
-
- S.error(pos, "comment not terminated");
-}
-
-
-func isLetter(ch int) bool {
- return
- 'a' <= ch && ch <= 'z' ||
- 'A' <= ch && ch <= 'Z' ||
- ch == '_' ||
- ch >= 0x80 && unicode.IsLetter(ch);
-}
-
-
-func isDigit(ch int) bool {
- return
- '0' <= ch && ch <= '9' ||
- ch >= 0x80 && unicode.IsDecimalDigit(ch);
-}
-
-
-func (S *Scanner) scanIdentifier() token.Token {
- pos := S.pos.Offset;
- for isLetter(S.ch) || isDigit(S.ch) {
- S.next();
- }
- return token.Lookup(S.src[pos : S.pos.Offset]);
-}
-
-
-func digitVal(ch int) int {
- switch {
- case '0' <= ch && ch <= '9': return ch - '0';
- case 'a' <= ch && ch <= 'f': return ch - 'a' + 10;
- case 'A' <= ch && ch <= 'F': return ch - 'A' + 10;
- }
- return 16; // larger than any legal digit val
-}
-
-
-func (S *Scanner) scanMantissa(base int) {
- for digitVal(S.ch) < base {
- S.next();
- }
-}
-
-
-func (S *Scanner) scanNumber(seen_decimal_point bool) token.Token {
- tok := token.INT;
-
- if seen_decimal_point {
- tok = token.FLOAT;
- S.scanMantissa(10);
- goto exponent;
- }
-
- if S.ch == '0' {
- // int or float
- S.next();
- if S.ch == 'x' || S.ch == 'X' {
- // hexadecimal int
- S.next();
- S.scanMantissa(16);
- } else {
- // octal int or float
- S.scanMantissa(8);
- if digitVal(S.ch) < 10 || S.ch == '.' || S.ch == 'e' || S.ch == 'E' {
- // float
- tok = token.FLOAT;
- goto mantissa;
- }
- // octal int
- }
- goto exit;
- }
-
-mantissa:
- // decimal int or float
- S.scanMantissa(10);
-
- if S.ch == '.' {
- // float
- tok = token.FLOAT;
- S.next();
- S.scanMantissa(10)
- }
-
-exponent:
- if S.ch == 'e' || S.ch == 'E' {
- // float
- tok = token.FLOAT;
- S.next();
- if S.ch == '-' || S.ch == '+' {
- S.next();
- }
- S.scanMantissa(10);
- }
-
-exit:
- return tok;
-}
-
-
-func (S *Scanner) scanDigits(base, length int) {
- for length > 0 && digitVal(S.ch) < base {
- S.next();
- length--;
- }
- if length > 0 {
- S.error(S.pos, "illegal char escape");
- }
-}
-
-
-func (S *Scanner) scanEscape(quote int) {
- pos := S.pos;
- ch := S.ch;
- S.next();
- switch ch {
- case 'a', 'b', 'f', 'n', 'r', 't', 'v', '\\', quote:
- // nothing to do
- case '0', '1', '2', '3', '4', '5', '6', '7':
- S.scanDigits(8, 3 - 1); // 1 char read already
- case 'x':
- S.scanDigits(16, 2);
- case 'u':
- S.scanDigits(16, 4);
- case 'U':
- S.scanDigits(16, 8);
- default:
- S.error(pos, "illegal char escape");
- }
-}
-
-
-func (S *Scanner) scanChar() {
- // '\'' already consumed
-
- ch := S.ch;
- S.next();
- if ch == '\\' {
- S.scanEscape('\'');
- }
-
- S.expect('\'');
-}
-
-
-func (S *Scanner) scanString(pos token.Position) {
- // '"' already consumed
-
- for S.ch != '"' {
- ch := S.ch;
- S.next();
- if ch == '\n' || ch < 0 {
- S.error(pos, "string not terminated");
- break;
- }
- if ch == '\\' {
- S.scanEscape('"');
- }
- }
-
- S.next();
-}
-
-
-func (S *Scanner) scanRawString(pos token.Position) {
- // '`' already consumed
-
- for S.ch != '`' {
- ch := S.ch;
- S.next();
- if ch == '\n' || ch < 0 {
- S.error(pos, "string not terminated");
- break;
- }
- }
-
- S.next();
-}
-
-
-// Helper functions for scanning multi-byte tokens such as >> += >>= .
-// Different routines recognize different length tok_i based on matches
-// of ch_i. If a token ends in '=', the result is tok1 or tok3
-// respectively. Otherwise, the result is tok0 if there was no other
-// matching character, or tok2 if the matching character was ch2.
-
-func (S *Scanner) switch2(tok0, tok1 token.Token) token.Token {
- if S.ch == '=' {
- S.next();
- return tok1;
- }
- return tok0;
-}
-
-
-func (S *Scanner) switch3(tok0, tok1 token.Token, ch2 int, tok2 token.Token) token.Token {
- if S.ch == '=' {
- S.next();
- return tok1;
- }
- if S.ch == ch2 {
- S.next();
- return tok2;
- }
- return tok0;
-}
-
-
-func (S *Scanner) switch4(tok0, tok1 token.Token, ch2 int, tok2, tok3 token.Token) token.Token {
- if S.ch == '=' {
- S.next();
- return tok1;
- }
- if S.ch == ch2 {
- S.next();
- if S.ch == '=' {
- S.next();
- return tok3;
- }
- return tok2;
- }
- return tok0;
-}
-
-
-// Scan scans the next token and returns the token position pos,
-// the token tok, and the literal text lit corresponding to the
-// token. The source end is indicated by token.EOF.
-//
-// For more tolerant parsing, Scan will return a valid token if
-// possible even if a syntax error was encountered. Thus, even
-// if the resulting token sequence contains no illegal tokens,
-// a client may not assume that no error occurred. Instead it
-// must check the scanner's ErrorCount or the number of calls
-// of the error handler, if there was one installed.
-//
-func (S *Scanner) Scan() (pos token.Position, tok token.Token, lit []byte) {
-scan_again:
- // skip white space
- for S.ch == ' ' || S.ch == '\t' || S.ch == '\n' || S.ch == '\r' {
- S.next();
- }
-
- // current token start
- pos, tok = S.pos, token.ILLEGAL;
-
- // determine token value
- switch ch := S.ch; {
- case isLetter(ch):
- tok = S.scanIdentifier();
- case digitVal(ch) < 10:
- tok = S.scanNumber(false);
- default:
- S.next(); // always make progress
- switch ch {
- case -1 : tok = token.EOF;
- case '"' : tok = token.STRING; S.scanString(pos);
- case '\'': tok = token.CHAR; S.scanChar();
- case '`' : tok = token.STRING; S.scanRawString(pos);
- case ':' : tok = S.switch2(token.COLON, token.DEFINE);
- case '.' :
- if digitVal(S.ch) < 10 {
- tok = S.scanNumber(true);
- } else if S.ch == '.' {
- S.next();
- if S.ch == '.' {
- S.next();
- tok = token.ELLIPSIS;
- }
- } else {
- tok = token.PERIOD;
- }
- case ',': tok = token.COMMA;
- case ';': tok = token.SEMICOLON;
- case '(': tok = token.LPAREN;
- case ')': tok = token.RPAREN;
- case '[': tok = token.LBRACK;
- case ']': tok = token.RBRACK;
- case '{': tok = token.LBRACE;
- case '}': tok = token.RBRACE;
- case '+': tok = S.switch3(token.ADD, token.ADD_ASSIGN, '+', token.INC);
- case '-': tok = S.switch3(token.SUB, token.SUB_ASSIGN, '-', token.DEC);
- case '*': tok = S.switch2(token.MUL, token.MUL_ASSIGN);
- case '/':
- if S.ch == '/' || S.ch == '*' {
- S.scanComment(pos);
- tok = token.COMMENT;
- if S.mode & ScanComments == 0 {
- goto scan_again;
- }
- } else {
- tok = S.switch2(token.QUO, token.QUO_ASSIGN);
- }
- case '%': tok = S.switch2(token.REM, token.REM_ASSIGN);
- case '^': tok = S.switch2(token.XOR, token.XOR_ASSIGN);
- case '<':
- if S.ch == '-' {
- S.next();
- tok = token.ARROW;
- } else {
- tok = S.switch4(token.LSS, token.LEQ, '<', token.SHL, token.SHL_ASSIGN);
- }
- case '>': tok = S.switch4(token.GTR, token.GEQ, '>', token.SHR, token.SHR_ASSIGN);
- case '=': tok = S.switch2(token.ASSIGN, token.EQL);
- case '!': tok = S.switch2(token.NOT, token.NEQ);
- case '&':
- if S.ch == '^' {
- S.next();
- tok = S.switch2(token.AND_NOT, token.AND_NOT_ASSIGN);
- } else {
- tok = S.switch3(token.AND, token.AND_ASSIGN, '&', token.LAND);
- }
- case '|': tok = S.switch3(token.OR, token.OR_ASSIGN, '|', token.LOR);
- default:
- if S.mode & AllowIllegalChars == 0 {
- S.error(pos, "illegal character " + charString(ch));
- }
- }
- }
-
- return pos, tok, S.src[pos.Offset : S.pos.Offset];
-}
-
-
-// Tokenize calls a function f with the token position, token value, and token
-// text for each token in the source src. The other parameters have the same
-// meaning as for the Init function. Tokenize keeps scanning until f returns
-// false (usually when the token value is token.EOF). The result is the number
-// of errors encountered.
-//
-func Tokenize(src []byte, err ErrorHandler, mode uint, f func (pos token.Position, tok token.Token, lit []byte) bool) int {
- var s Scanner;
- s.Init(src, err, mode);
- for f(s.Scan()) {
- // action happens in f
- }
- return s.ErrorCount;
-}
generated by cgit v1.2.3 (git 2.39.1) at 2025-05-01 20:35:50 +0000