cpython/Parser/tokenizer.c

/***********************************************************
Copyright (c) 2000, BeOpen.com.
Copyright (c) 1995-2000, Corporation for National Research Initiatives.
Copyright (c) 1990-1995, Stichting Mathematisch Centrum.
All rights reserved.

See the file "Misc/COPYRIGHT" for information on usage and
redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
******************************************************************/

/* Tokenizer implementation */

#include "pgenheaders.h"

#include <ctype.h>

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

extern char *PyOS_Readline(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(void);
static int tok_nextc(struct tok_state *tok);
static void tok_backup(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(void)
{
	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(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(FILE *fp, char *ps1, char *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(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(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') {
				PyMem_FREE(new);
				tok->done = E_EOF;
			}
			else if (tok->start != NULL) {
				size_t start = tok->start - tok->buf;
				size_t oldlen = tok->cur - tok->buf;
				size_t newlen = oldlen + strlen(new);
				char *buf = tok->buf;
				PyMem_RESIZE(buf, char, newlen+1);
				tok->lineno++;
				if (buf == NULL) {
					PyMem_DEL(tok->buf);
					tok->buf = NULL;
					PyMem_FREE(new);
					tok->done = E_NOMEM;
					return EOF;
				}
				tok->buf = buf;
				tok->cur = tok->buf + oldlen;
				strcpy(tok->buf + oldlen, new);
				PyMem_FREE(new);
				tok->inp = tok->buf + newlen;
				tok->end = tok->inp + 1;
				tok->start = tok->buf + start;
			}
			else {
				tok->lineno++;
				if (tok->buf != NULL)
					PyMem_DEL(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(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(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(int c1, int 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(struct tok_state *tok)
{
	if (tok->alterror) {
		tok->done = E_TABSPACE;
		tok->cur = tok->inp;
		return 1;
	}
	if (tok->altwarning) {
		PySys_WriteStderr("%s: inconsistent use of tabs and spaces "
                                  "in indentation\n", tok->filename);
		tok->altwarning = 0;
	}
	return 0;
}


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

int
PyTokenizer_Get(register struct tok_state *tok, char **p_start,
		char **p_end)
{
	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) {
					tok->done = E_TOODEEP;
					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]) {
					tok->done = E_DEDENT;
					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, while looking for tab-setting magic */
	if (c == '#') {
		static char *tabforms[] = {
			"tab-width:",		/* Emacs */
			":tabstop=",		/* vim, full form */
			":ts=",			/* vim, abbreviated form */
			"set tabsize=",		/* will vi never die? */
		/* more templates can be added here to support other editors */
		};
		char cbuf[80];
		char *tp, **cp;
		tp = cbuf;
		do {
			*tp++ = c = tok_nextc(tok);
		} while (c != EOF && c != '\n' &&
			 tp - cbuf + 1 < sizeof(cbuf));
		*tp = '\0';
		for (cp = tabforms; 
		     cp < tabforms + sizeof(tabforms)/sizeof(tabforms[0]);
		     cp++) {
			if ((tp = strstr(cbuf, *cp))) {
				int newsize = atoi(tp + strlen(*cp));

				if (newsize >= 1 && newsize <= 40) {
					tok->tabsize = newsize;
					if (Py_VerboseFlag)
					    PySys_WriteStderr(
						"Tab size set to %d\n",
						newsize);
				}
			}
		}
		while (c != EOF && c != '\n')
			c = tok_nextc(tok);
	}
	
	/* 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(int type, char *start, char *end)
{
	printf("%s", _PyParser_TokenNames[type]);
	if (type == NAME || type == NUMBER || type == STRING || type == OP)
		printf("(%.*s)", (int)(end - start), start);
}

#endif