cpython/Parser/tokenizer.c

/***********************************************************
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation, and that the names of Stichting Mathematisch
Centrum or CWI or Corporation for National Research Initiatives or
CNRI not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

While CWI is the initial source for this software, a modified version
is made available by the Corporation for National Research Initiatives
(CNRI) at the Internet address ftp://ftp.python.org.

STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
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PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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******************************************************************/

/* Tokenizer implementation */

#include "pgenheaders.h"

#include <ctype.h>

#include "tokenizer.h"
#include "errcode.h"

extern char *PyOS_Readline Py_PROTO((char *));
/* Return malloc'ed string including trailing \n;
   empty malloc'ed string for EOF;
   NULL if interrupted */

/* Don't ever change this -- it would break the portability of Python code */
#define TABSIZE 8

/* Convert a possibly signed character to a nonnegative int */
/* XXX This assumes characters are 8 bits wide */
#ifdef __CHAR_UNSIGNED__
#define Py_CHARMASK(c)		(c)
#else
#define Py_CHARMASK(c)		((c) & 0xff)
#endif

/* Forward */
static struct tok_state *tok_new Py_PROTO((void));
static int tok_nextc Py_PROTO((struct tok_state *tok));
static void tok_backup Py_PROTO((struct tok_state *tok, int c));

/* Token names */

char *_PyParser_TokenNames[] = {
	"ENDMARKER",
	"NAME",
	"NUMBER",
	"STRING",
	"NEWLINE",
	"INDENT",
	"DEDENT",
	"LPAR",
	"RPAR",
	"LSQB",
	"RSQB",
	"COLON",
	"COMMA",
	"SEMI",
	"PLUS",
	"MINUS",
	"STAR",
	"SLASH",
	"VBAR",
	"AMPER",
	"LESS",
	"GREATER",
	"EQUAL",
	"DOT",
	"PERCENT",
	"BACKQUOTE",
	"LBRACE",
	"RBRACE",
	"EQEQUAL",
	"NOTEQUAL",
	"LESSEQUAL",
	"GREATEREQUAL",
	"TILDE",
	"CIRCUMFLEX",
	"LEFTSHIFT",
	"RIGHTSHIFT",
	"DOUBLESTAR",
	/* This table must match the #defines in token.h! */
	"OP",
	"<ERRORTOKEN>",
	"<N_TOKENS>"
};


/* Create and initialize a new tok_state structure */

static struct tok_state *
tok_new()
{
	struct tok_state *tok = PyMem_NEW(struct tok_state, 1);
	if (tok == NULL)
		return NULL;
	tok->buf = tok->cur = tok->end = tok->inp = tok->start = NULL;
	tok->done = E_OK;
	tok->fp = NULL;
	tok->tabsize = TABSIZE;
	tok->indent = 0;
	tok->indstack[0] = 0;
	tok->atbol = 1;
	tok->pendin = 0;
	tok->prompt = tok->nextprompt = NULL;
	tok->lineno = 0;
	tok->level = 0;
	tok->filename = NULL;
	tok->altwarning = 0;
	tok->alterror = 0;
	tok->alttabsize = 1;
	tok->altindstack[0] = 0;
	return tok;
}


/* Set up tokenizer for string */

struct tok_state *
PyTokenizer_FromString(str)
	char *str;
{
	struct tok_state *tok = tok_new();
	if (tok == NULL)
		return NULL;
	tok->buf = tok->cur = tok->end = tok->inp = str;
	return tok;
}


/* Set up tokenizer for file */

struct tok_state *
PyTokenizer_FromFile(fp, ps1, ps2)
	FILE *fp;
	char *ps1, *ps2;
{
	struct tok_state *tok = tok_new();
	if (tok == NULL)
		return NULL;
	if ((tok->buf = PyMem_NEW(char, BUFSIZ)) == NULL) {
		PyMem_DEL(tok);
		return NULL;
	}
	tok->cur = tok->inp = tok->buf;
	tok->end = tok->buf + BUFSIZ;
	tok->fp = fp;
	tok->prompt = ps1;
	tok->nextprompt = ps2;
	return tok;
}


/* Free a tok_state structure */

void
PyTokenizer_Free(tok)
	struct tok_state *tok;
{
	if (tok->fp != NULL && tok->buf != NULL)
		PyMem_DEL(tok->buf);
	PyMem_DEL(tok);
}


/* Get next char, updating state; error code goes into tok->done */

static int
tok_nextc(tok)
	register struct tok_state *tok;
{
	for (;;) {
		if (tok->cur != tok->inp) {
			return Py_CHARMASK(*tok->cur++); /* Fast path */
		}
		if (tok->done != E_OK)
			return EOF;
		if (tok->fp == NULL) {
			char *end = strchr(tok->inp, '\n');
			if (end != NULL)
				end++;
			else {
				end = strchr(tok->inp, '\0');
				if (end == tok->inp) {
					tok->done = E_EOF;
					return EOF;
				}
			}
			if (tok->start == NULL)
				tok->buf = tok->cur;
			tok->lineno++;
			tok->inp = end;
			return Py_CHARMASK(*tok->cur++);
		}
		if (tok->prompt != NULL) {
			char *new = PyOS_Readline(tok->prompt);
			if (tok->nextprompt != NULL)
				tok->prompt = tok->nextprompt;
			if (new == NULL)
				tok->done = E_INTR;
			else if (*new == '\0') {
				free(new);
				tok->done = E_EOF;
			}
			else if (tok->start != NULL) {
				int start = tok->start - tok->buf;
				int oldlen = tok->cur - tok->buf;
				int newlen = oldlen + strlen(new);
				char *buf = realloc(tok->buf, newlen+1);
				tok->lineno++;
				if (buf == NULL) {
					free(tok->buf);
					tok->buf = NULL;
					free(new);
					tok->done = E_NOMEM;
					return EOF;
				}
				tok->buf = buf;
				tok->cur = tok->buf + oldlen;
				strcpy(tok->buf + oldlen, new);
				free(new);
				tok->inp = tok->buf + newlen;
				tok->end = tok->inp + 1;
				tok->start = tok->buf + start;
			}
			else {
				tok->lineno++;
				if (tok->buf != NULL)
					free(tok->buf);
				tok->buf = new;
				tok->cur = tok->buf;
				tok->inp = strchr(tok->buf, '\0');
				tok->end = tok->inp + 1;
			}
		}
		else {
			int done = 0;
			int cur = 0;
			char *pt;
			if (tok->start == NULL) {
				if (tok->buf == NULL) {
					tok->buf = PyMem_NEW(char, BUFSIZ);
					if (tok->buf == NULL) {
						tok->done = E_NOMEM;
						return EOF;
					}
					tok->end = tok->buf + BUFSIZ;
				}
				if (fgets(tok->buf, (int)(tok->end - tok->buf),
					  tok->fp) == NULL) {
					tok->done = E_EOF;
					done = 1;
				}
				else {
					tok->done = E_OK;
					tok->inp = strchr(tok->buf, '\0');
					done = tok->inp[-1] == '\n';
				}
			}
			else {
				cur = tok->cur - tok->buf;
				if (feof(tok->fp)) {
					tok->done = E_EOF;
					done = 1;
				}
				else
					tok->done = E_OK;
			}
			tok->lineno++;
			/* Read until '\n' or EOF */
			while (!done) {
				int curstart = tok->start == NULL ? -1 :
					       tok->start - tok->buf;
				int curvalid = tok->inp - tok->buf;
				int newsize = curvalid + BUFSIZ;
				char *newbuf = tok->buf;
				PyMem_RESIZE(newbuf, char, newsize);
				if (newbuf == NULL) {
					tok->done = E_NOMEM;
					tok->cur = tok->inp;
					return EOF;
				}
				tok->buf = newbuf;
				tok->inp = tok->buf + curvalid;
				tok->end = tok->buf + newsize;
				tok->start = curstart < 0 ? NULL :
					     tok->buf + curstart;
				if (fgets(tok->inp,
					       (int)(tok->end - tok->inp),
					       tok->fp) == NULL) {
					/* Last line does not end in \n,
					   fake one */
					strcpy(tok->inp, "\n");
				}
				tok->inp = strchr(tok->inp, '\0');
				done = tok->inp[-1] == '\n';
			}
			tok->cur = tok->buf + cur;
#ifndef macintosh
			/* replace "\r\n" with "\n" */
			/* For Mac we leave the \r, giving a syntax error */
			pt = tok->inp - 2;
			if (pt >= tok->buf && *pt == '\r') {
				*pt++ = '\n';
				*pt = '\0';
				tok->inp = pt;
			}
#endif
		}
		if (tok->done != E_OK) {
			if (tok->prompt != NULL)
				PySys_WriteStderr("\n");
			tok->cur = tok->inp;
			return EOF;
		}
	}
	/*NOTREACHED*/
}


/* Back-up one character */

static void
tok_backup(tok, c)
	register struct tok_state *tok;
	register int c;
{
	if (c != EOF) {
		if (--tok->cur < tok->buf)
			Py_FatalError("tok_backup: begin of buffer");
		if (*tok->cur != c)
			*tok->cur = c;
	}
}


/* Return the token corresponding to a single character */

int
PyToken_OneChar(c)
	int c;
{
	switch (c) {
	case '(':	return LPAR;
	case ')':	return RPAR;
	case '[':	return LSQB;
	case ']':	return RSQB;
	case ':':	return COLON;
	case ',':	return COMMA;
	case ';':	return SEMI;
	case '+':	return PLUS;
	case '-':	return MINUS;
	case '*':	return STAR;
	case '/':	return SLASH;
	case '|':	return VBAR;
	case '&':	return AMPER;
	case '<':	return LESS;
	case '>':	return GREATER;
	case '=':	return EQUAL;
	case '.':	return DOT;
	case '%':	return PERCENT;
	case '`':	return BACKQUOTE;
	case '{':	return LBRACE;
	case '}':	return RBRACE;
	case '^':	return CIRCUMFLEX;
	case '~':	return TILDE;
	default:	return OP;
	}
}


int
PyToken_TwoChars(c1, c2)
	int c1, c2;
{
	switch (c1) {
	case '=':
		switch (c2) {
		case '=':	return EQEQUAL;
		}
		break;
	case '!':
		switch (c2) {
		case '=':	return NOTEQUAL;
		}
		break;
	case '<':
		switch (c2) {
		case '>':	return NOTEQUAL;
		case '=':	return LESSEQUAL;
		case '<':	return LEFTSHIFT;
		}
		break;
	case '>':
		switch (c2) {
		case '=':	return GREATEREQUAL;
		case '>':	return RIGHTSHIFT;
		}
		break;
	case '*':
		switch (c2) {
		case '*':	return DOUBLESTAR;
		}
		break;
	}
	return OP;
}


static int
indenterror(tok)
	struct tok_state *tok;
{
	if (tok->alterror) {
		tok->done = E_INDENT;
		tok->cur = tok->inp;
		return 1;
	}
	if (tok->altwarning) {
		PySys_WriteStderr("%s: inconsistent tab/space usage\n",
			tok->filename);
		tok->altwarning = 0;
	}
	return 0;
}


/* Get next token, after space stripping etc. */

int
PyTokenizer_Get(tok, p_start, p_end)
	register struct tok_state *tok; /* In/out: tokenizer state */
	char **p_start, **p_end; /* Out: point to start/end of token */
{
	register int c;
	int blankline;

	*p_start = *p_end = NULL;
  nextline:
	tok->start = NULL;
	blankline = 0;

	/* Get indentation level */
	if (tok->atbol) {
		register int col = 0;
		register int altcol = 0;
		tok->atbol = 0;
		for (;;) {
			c = tok_nextc(tok);
			if (c == ' ')
				col++, altcol++;
			else if (c == '\t') {
				col = (col/tok->tabsize + 1) * tok->tabsize;
				altcol = (altcol/tok->alttabsize + 1)
					* tok->alttabsize;
			}
			else if (c == '\014') /* Control-L (formfeed) */
				col = altcol = 0; /* For Emacs users */
			else
				break;
		}
		tok_backup(tok, c);
		if (c == '#' || c == '\n') {
			/* Lines with only whitespace and/or comments
			   shouldn't affect the indentation and are
			   not passed to the parser as NEWLINE tokens,
			   except *totally* empty lines in interactive
			   mode, which signal the end of a command group. */
			if (col == 0 && c == '\n' && tok->prompt != NULL)
				blankline = 0; /* Let it through */
			else
				blankline = 1; /* Ignore completely */
			/* We can't jump back right here since we still
			   may need to skip to the end of a comment */
		}
		if (!blankline && tok->level == 0) {
			if (col == tok->indstack[tok->indent]) {
				/* No change */
				if (altcol != tok->altindstack[tok->indent]) {
					if (indenterror(tok))
						return ERRORTOKEN;
				}
			}
			else if (col > tok->indstack[tok->indent]) {
				/* Indent -- always one */
				if (tok->indent+1 >= MAXINDENT) {
					PySys_WriteStderr(
						"excessive indent\n");
					tok->done = E_TOKEN;
					tok->cur = tok->inp;
					return ERRORTOKEN;
				}
				if (altcol <= tok->altindstack[tok->indent]) {
					if (indenterror(tok))
						return ERRORTOKEN;
				}
				tok->pendin++;
				tok->indstack[++tok->indent] = col;
				tok->altindstack[tok->indent] = altcol;
			}
			else /* col < tok->indstack[tok->indent] */ {
				/* Dedent -- any number, must be consistent */
				while (tok->indent > 0 &&
					col < tok->indstack[tok->indent]) {
					tok->pendin--;
					tok->indent--;
				}
				if (col != tok->indstack[tok->indent]) {
					PySys_WriteStderr(
						"inconsistent dedent\n");
					tok->done = E_TOKEN;
					tok->cur = tok->inp;
					return ERRORTOKEN;
				}
				if (altcol != tok->altindstack[tok->indent]) {
					if (indenterror(tok))
						return ERRORTOKEN;
				}
			}
		}
	}
	
	tok->start = tok->cur;
	
	/* Return pending indents/dedents */
	if (tok->pendin != 0) {
		if (tok->pendin < 0) {
			tok->pendin++;
			return DEDENT;
		}
		else {
			tok->pendin--;
			return INDENT;
		}
	}
	
 again:
	tok->start = NULL;
	/* Skip spaces */
	do {
		c = tok_nextc(tok);
	} while (c == ' ' || c == '\t' || c == '\014');
	
	/* Set start of current token */
	tok->start = tok->cur - 1;
	
	/* Skip comment */
	if (c == '#') {
		/* Hack to allow overriding the tabsize in the file.
		   This is also recognized by vi, when it occurs near the
		   beginning or end of the file.  (Will vi never die...?)
		   For Python it must be at the beginning of the file! */
		/* XXX The real vi syntax is actually different :-( */
		/* XXX Should recognize Emacs syntax, too */
		int x;
		if (sscanf(tok->cur,
				" vi:set tabsize=%d:", &x) == 1 &&
						x >= 1 && x <= 40) {
			/* PySys_WriteStderr("# vi:set tabsize=%d:\n", x); */
			tok->tabsize = x;
		}
		do {
			c = tok_nextc(tok);
		} while (c != EOF && c != '\n');
	}
	
	/* Check for EOF and errors now */
	if (c == EOF) {
		return tok->done == E_EOF ? ENDMARKER : ERRORTOKEN;
	}
	
	/* Identifier (most frequent token!) */
	if (isalpha(c) || c == '_') {
		/* Process r"", u"" and ur"" */
		switch (c) {
		case 'r':
		case 'R':
			c = tok_nextc(tok);
			if (c == '"' || c == '\'')
				goto letter_quote;
			break;
		case 'u':
		case 'U':
			c = tok_nextc(tok);
			if (c == 'r' || c == 'R')
				c = tok_nextc(tok);
			if (c == '"' || c == '\'')
				goto letter_quote;
			break;
		}
		while (isalnum(c) || c == '_') {
			c = tok_nextc(tok);
		}
		tok_backup(tok, c);
		*p_start = tok->start;
		*p_end = tok->cur;
		return NAME;
	}
	
	/* Newline */
	if (c == '\n') {
		tok->atbol = 1;
		if (blankline || tok->level > 0)
			goto nextline;
		*p_start = tok->start;
		*p_end = tok->cur - 1; /* Leave '\n' out of the string */
		return NEWLINE;
	}
	
#ifdef macintosh
	if (c == '\r') {
		PySys_WriteStderr(
		  "File contains \\r characters (incorrect line endings?)\n");
		tok->done = E_TOKEN;
		tok->cur = tok->inp;
		return ERRORTOKEN;
	}
#endif	
	/* Period or number starting with period? */
	if (c == '.') {
		c = tok_nextc(tok);
		if (isdigit(c)) {
			goto fraction;
		}
		else {
			tok_backup(tok, c);
			*p_start = tok->start;
			*p_end = tok->cur;
			return DOT;
		}
	}

	/* Number */
	if (isdigit(c)) {
		if (c == '0') {
			/* Hex or octal */
			c = tok_nextc(tok);
			if (c == '.')
				goto fraction;
#ifndef WITHOUT_COMPLEX
			if (c == 'j' || c == 'J')
				goto imaginary;
#endif
			if (c == 'x' || c == 'X') {
				/* Hex */
				do {
					c = tok_nextc(tok);
				} while (isxdigit(c));
			}
			else {
				/* XXX This is broken!  E.g.,
				   09.9 should be accepted as float! */
				/* Octal; c is first char of it */
				/* There's no 'isoctdigit' macro, sigh */
				while ('0' <= c && c < '8') {
					c = tok_nextc(tok);
				}
			}
			if (c == 'l' || c == 'L')
				c = tok_nextc(tok);
		}
		else {
			/* Decimal */
			do {
				c = tok_nextc(tok);
			} while (isdigit(c));
			if (c == 'l' || c == 'L')
				c = tok_nextc(tok);
			else {
				/* Accept floating point numbers.
				   XXX This accepts incomplete things like
				   XXX 12e or 1e+; worry run-time */
				if (c == '.') {
		fraction:
					/* Fraction */
					do {
						c = tok_nextc(tok);
					} while (isdigit(c));
				}
				if (c == 'e' || c == 'E') {
					/* Exponent part */
					c = tok_nextc(tok);
					if (c == '+' || c == '-')
						c = tok_nextc(tok);
					while (isdigit(c)) {
						c = tok_nextc(tok);
					}
				}
#ifndef WITHOUT_COMPLEX
				if (c == 'j' || c == 'J')
					/* Imaginary part */
		imaginary:
					c = tok_nextc(tok);
#endif
			}
		}
		tok_backup(tok, c);
		*p_start = tok->start;
		*p_end = tok->cur;
		return NUMBER;
	}

  letter_quote:
	/* String */
	if (c == '\'' || c == '"') {
		int quote2 = tok->cur - tok->start + 1;
		int quote = c;
		int triple = 0;
		int tripcount = 0;
		for (;;) {
			c = tok_nextc(tok);
			if (c == '\n') {
				if (!triple) {
					tok->done = E_TOKEN;
					tok_backup(tok, c);
					return ERRORTOKEN;
				}
				tripcount = 0;
			}
			else if (c == EOF) {
				tok->done = E_TOKEN;
				tok->cur = tok->inp;
				return ERRORTOKEN;
			}
			else if (c == quote) {
				tripcount++;
				if (tok->cur - tok->start == quote2) {
					c = tok_nextc(tok);
					if (c == quote) {
						triple = 1;
						tripcount = 0;
						continue;
					}
					tok_backup(tok, c);
				}
				if (!triple || tripcount == 3)
					break;
			}
			else if (c == '\\') {
				tripcount = 0;
				c = tok_nextc(tok);
				if (c == EOF) {
					tok->done = E_TOKEN;
					tok->cur = tok->inp;
					return ERRORTOKEN;
				}
			}
			else
				tripcount = 0;
		}
		*p_start = tok->start;
		*p_end = tok->cur;
		return STRING;
	}
	
	/* Line continuation */
	if (c == '\\') {
		c = tok_nextc(tok);
		if (c != '\n') {
			tok->done = E_TOKEN;
			tok->cur = tok->inp;
			return ERRORTOKEN;
		}
		goto again; /* Read next line */
	}
	
	/* Check for two-character token */
	{
		int c2 = tok_nextc(tok);
		int token = PyToken_TwoChars(c, c2);
		if (token != OP) {
			*p_start = tok->start;
			*p_end = tok->cur;
			return token;
		}
		tok_backup(tok, c2);
	}
	
	/* Keep track of parentheses nesting level */
	switch (c) {
	case '(':
	case '[':
	case '{':
		tok->level++;
		break;
	case ')':
	case ']':
	case '}':
		tok->level--;
		break;
	}
	
	/* Punctuation character */
	*p_start = tok->start;
	*p_end = tok->cur;
	return PyToken_OneChar(c);
}


#ifdef Py_DEBUG

void
tok_dump(type, start, end)
	int type;
	char *start, *end;
{
	printf("%s", _PyParser_TokenNames[type]);
	if (type == NAME || type == NUMBER || type == STRING || type == OP)
		printf("(%.*s)", (int)(end - start), start);
}

#endif