/* Tokenizer implementation */

/* XXX This is rather old, should be restructured perhaps */
/* XXX Need a better interface to report errors than writing to stderr */

#include <stdio.h>
#include <ctype.h>
#include "string.h"

#include "PROTO.h"
#include "malloc.h"
#include "tokenizer.h"
#include "errcode.h"

#ifdef THINK_C
#define TABSIZE 4
#endif

#ifndef TABSIZE
#define TABSIZE 8
#endif

/* Token names */

char *tok_name[] = {
	"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",
	"OP",
	"<ERRORTOKEN>",
	"<N_TOKENS>"
};


/* Create and initialize a new tok_state structure */

static struct tok_state *
tok_new()
{
	struct tok_state *tok = NEW(struct tok_state, 1);
	if (tok == NULL)
		return NULL;
	tok->buf = tok->cur = tok->end = tok->inp = 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;
	return tok;
}


/* Set up tokenizer for string */

struct tok_state *
tok_setups(str)
	char *str;
{
	struct tok_state *tok = tok_new();
	if (tok == NULL)
		return NULL;
	tok->buf = tok->cur = str;
	tok->end = tok->inp = strchr(str, '\0');
	return tok;
}


/* Set up tokenizer for string */

struct tok_state *
tok_setupf(fp, ps1, ps2)
	FILE *fp;
	char *ps1, *ps2;
{
	struct tok_state *tok = tok_new();
	if (tok == NULL)
		return NULL;
	if ((tok->buf = NEW(char, BUFSIZ)) == NULL) {
		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
tok_free(tok)
	struct tok_state *tok;
{
	/* XXX really need a separate flag to say 'my buffer' */
	if (tok->fp != NULL && tok->buf != NULL)
		DEL(tok->buf);
	DEL(tok);
}


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

static int
tok_nextc(tok)
	register struct tok_state *tok;
{
	if (tok->done != E_OK)
		return EOF;
	
	for (;;) {
		if (tok->cur < tok->inp)
			return *tok->cur++;
		if (tok->fp == NULL) {
			tok->done = E_EOF;
			return EOF;
		}
		if (tok->inp > tok->buf && tok->inp[-1] == '\n')
			tok->inp = tok->buf;
		if (tok->inp == tok->end) {
			int n = tok->end - tok->buf;
			char *new = tok->buf;
			RESIZE(new, char, n+n);
			if (new == NULL) {
				fprintf(stderr, "tokenizer out of mem\n");
				tok->done = E_NOMEM;
				return EOF;
			}
			tok->buf = new;
			tok->inp = tok->buf + n;
			tok->end = tok->inp + n;
		}
#ifdef USE_READLINE
		if (tok->prompt != NULL) {
			extern char *readline PROTO((char *prompt));
			static int been_here;
			if (!been_here) {
				/* Force rebind of TAB to insert-tab */
				extern int rl_insert();
				rl_bind_key('\t', rl_insert);
				been_here++;
			}
			if (tok->buf != NULL)
				free(tok->buf);
			tok->buf = readline(tok->prompt);
			(void) intrcheck(); /* Clear pending interrupt */
			if (tok->nextprompt != NULL)
				tok->prompt = tok->nextprompt;
				/* XXX different semantics w/o readline()! */
			if (tok->buf == NULL) {
				tok->done = E_EOF;
			}
			else {
				unsigned int n = strlen(tok->buf);
				if (n > 0)
					add_history(tok->buf);
				/* Append the '\n' that readline()
				   doesn't give us, for the tokenizer... */
				tok->buf = realloc(tok->buf, n+2);
				if (tok->buf == NULL)
					tok->done = E_NOMEM;
				else {
					tok->end = tok->buf + n;
					*tok->end++ = '\n';
					*tok->end = '\0';
					tok->inp = tok->end;
					tok->cur = tok->buf;
				}
			}
		}
		else
#endif
		{
			tok->cur = tok->inp;
			if (tok->prompt != NULL && tok->inp == tok->buf) {
				fprintf(stderr, "%s", tok->prompt);
				tok->prompt = tok->nextprompt;
			}
			tok->done = fgets_intr(tok->inp,
				(int)(tok->end - tok->inp), tok->fp);
		}
		if (tok->done != E_OK) {
			if (tok->prompt != NULL)
				fprintf(stderr, "\n");
			return EOF;
		}
		tok->inp = strchr(tok->inp, '\0');
	}
}


/* 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) {
			fprintf(stderr, "tok_backup: begin of buffer\n");
			abort();
		}
		if (*tok->cur != c)
			*tok->cur = c;
	}
}


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

int
tok_1char(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;
	default:	return OP;
	}
}


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

int
tok_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;
	
	/* Get indentation level */
	if (tok->atbol) {
		register int col = 0;
		tok->atbol = 0;
		tok->lineno++;
		for (;;) {
			c = tok_nextc(tok);
			if (c == ' ')
				col++;
			else if (c == '\t')
				col = (col/tok->tabsize + 1) * tok->tabsize;
			else
				break;
		}
		tok_backup(tok, c);
		if (col == tok->indstack[tok->indent]) {
			/* No change */
		}
		else if (col > tok->indstack[tok->indent]) {
			/* Indent -- always one */
			if (tok->indent+1 >= MAXINDENT) {
				fprintf(stderr, "excessive indent\n");
				tok->done = E_TOKEN;
				return ERRORTOKEN;
			}
			tok->pendin++;
			tok->indstack[++tok->indent] = col;
		}
		else /* col < tok->indstack[tok->indent] */ {
			/* Dedent -- any number, must be consistent */
			while (tok->indent > 0 &&
				col < tok->indstack[tok->indent]) {
				tok->indent--;
				tok->pendin--;
			}
			if (col != tok->indstack[tok->indent]) {
				fprintf(stderr, "inconsistent dedent\n");
				tok->done = E_TOKEN;
				return ERRORTOKEN;
			}
		}
	}
	
	*p_start = *p_end = tok->cur;
	
	/* Return pending indents/dedents */
	if (tok->pendin != 0) {
		if (tok->pendin < 0) {
			tok->pendin++;
			return DEDENT;
		}
		else {
			tok->pendin--;
			return INDENT;
		}
	}
	
 again:
	/* Skip spaces */
	do {
		c = tok_nextc(tok);
	} while (c == ' ' || c == '\t');
	
	/* Set start of current token */
	*p_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...?) */
		int x;
		if (sscanf(tok->cur, " vi:set tabsize=%d:", &x) == 1 &&
						x >= 1 && x <= 40) {
			fprintf(stderr, "# 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 == '_') {
		do {
			c = tok_nextc(tok);
		} while (isalnum(c) || c == '_');
		tok_backup(tok, c);
		*p_end = tok->cur;
		return NAME;
	}
	
	/* Newline */
	if (c == '\n') {
		tok->atbol = 1;
		*p_end = tok->cur - 1; /* Leave '\n' out of the string */
		return NEWLINE;
	}
	
	/* Number */
	if (isdigit(c)) {
		if (c == '0') {
			/* Hex or octal */
			c = tok_nextc(tok);
			if (c == '.')
				goto fraction;
			if (c == 'x' || c == 'X') {
				/* Hex */
				do {
					c = tok_nextc(tok);
				} while (isxdigit(c));
			}
			else {
				/* Octal; c is first char of it */
				/* There's no 'isoctdigit' macro, sigh */
				while ('0' <= c && c < '8') {
					c = tok_nextc(tok);
				}
			}
		}
		else {
			/* Decimal */
			do {
				c = tok_nextc(tok);
			} while (isdigit(c));
			/* Accept floating point numbers.
			   XXX This accepts incomplete things like 12e or 1e+;
			       worry about that at run-time.
			   XXX Doesn't accept numbers starting with a dot */
			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);
				}
			}
		}
		tok_backup(tok, c);
		*p_end = tok->cur;
		return NUMBER;
	}
	
	/* String */
	if (c == '\'') {
		for (;;) {
			c = tok_nextc(tok);
			if (c == '\n' || c == EOF) {
				tok->done = E_TOKEN;
				return ERRORTOKEN;
			}
			if (c == '\\') {
				c = tok_nextc(tok);
				*p_end = tok->cur;
				if (c == '\n' || c == EOF) {
					tok->done = E_TOKEN;
					return ERRORTOKEN;
				}
				continue;
			}
			if (c == '\'')
				break;
		}
		*p_end = tok->cur;
		return STRING;
	}
	
	/* Line continuation */
	if (c == '\\') {
		c = tok_nextc(tok);
		if (c != '\n') {
			tok->done = E_TOKEN;
			return ERRORTOKEN;
		}
		goto again; /* Read next line */
	}
	
	/* Punctuation character */
	*p_end = tok->cur;
	return tok_1char(c);
}


#ifdef DEBUG

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

#endif