[fcformat] Add support for subexpressions

[fontconfig.git] / src / fcformat.c

/*
 * Copyright © 2008 Red Hat, Inc.
 *
 * Red Hat Author(s): Behdad Esfahbod
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, 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 name of Keith Packard not be used in
 * advertising or publicity pertaining to distribution of the software without
 * specific, written prior permission.  Keith Packard makes no
 * representations about the suitability of this software for any purpose.  It
 * is provided "as is" without express or implied warranty.
 *
 * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#include "fcint.h"
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>


static void
message (const char *fmt, ...)
{
    va_list	args;
    va_start (args, fmt);
    fprintf (stderr, "Fontconfig: Pattern format error:");
    vfprintf (stderr, fmt, args);
    fprintf (stderr, ".\n");
    va_end (args);
}


typedef struct _FcFormatContext
{
    const FcChar8 *format_orig;
    const FcChar8 *format;
    int            format_len;
    FcChar8       *scratch;
} FcFormatContext;

static void
FcFormatContextInit (FcFormatContext *c,
		     const FcChar8   *format)
{
    c->format_orig = c->format = format;
    c->format_len = strlen ((const char *) format);
    c->scratch = malloc (c->format_len + 1);
}

static void
FcFormatContextDone (FcFormatContext *c)
{
    if (c)
    {
	free (c->scratch);
    }
}

static FcBool
consume_char (FcFormatContext *c,
	      FcChar8          term)
{
    if (*c->format != term)
	return FcFalse;

    c->format++;
    return FcTrue;
}

static FcBool
expect_char (FcFormatContext *c,
	      FcChar8          term)
{
    FcBool res = consume_char (c, term);
    if (!res)
    {
	if (c->format == c->format_orig + c->format_len)
	    message ("format ended while expecting '%c'",
		     term);
	else
	    message ("expected '%c' at %d",
		     term, c->format - c->format_orig + 1);
    }
    return res;
}

static FcBool
FcCharIsPunct (const FcChar8 c)
{
    if (c < '0')
	return FcTrue;
    if (c <= '9')
	return FcFalse;
    if (c < 'A')
	return FcTrue;
    if (c <= 'Z')
	return FcFalse;
    if (c < 'a')
	return FcTrue;
    if (c <= 'z')
	return FcFalse;
    if (c <= '~')
	return FcTrue;
    return FcFalse;
}

static FcBool
read_elt_name_to_scratch (FcFormatContext *c)
{
    FcChar8 *p;

    p = c->scratch;

    while (*c->format)
    {
	if (*c->format == '\\')
	{
	    c->format++;
	    if (*c->format)
		c->format++;
	    continue;
	}
	else if (FcCharIsPunct (*c->format))
	    break;

	*p++ = *c->format++;
    }
    *p = '\0';

    if (p == c->scratch)
    {
	message ("expected element name at %d",
		 c->format - c->format_orig + 1);
	return FcFalse;
    }

    return FcTrue;
}

static void
interpret (FcFormatContext *c,
	   FcPattern       *pat,
	   FcStrBuf        *buf,
	   FcChar8          term);

static void
interpret_percent (FcFormatContext *c,
		   FcPattern       *pat,
		   FcStrBuf        *buf)
{
    int           width, before;
    FcChar8      *p;
    FcPatternElt *e;

    FcPattern    *subpat = pat;
    FcBool        add_colon = FcFalse;
    FcBool        add_elt_name = FcFalse;

    if (!expect_char (c, '%'))
	return;

    if (consume_char (c, '%')) /* "%%" */
    {
	FcStrBufChar (buf, '%');
	return;
    }

    /* parse an optional width specifier */
    width = strtol ((const char *) c->format, (char **) &c->format, 10);

    before = buf->len;

    if (!expect_char (c, '{'))
	goto bail;

    if (consume_char (c, '{'))
    {
	/* it's just a subexpression.  no tag involved */
	interpret (c, pat, buf, '}');
	expect_char (c, '}');
	goto filter;
    }

    switch (*c->format) {
    case ':':
	add_colon = FcTrue;
	consume_char (c, ':');
	break;
    }

parse_tag:
    if (!read_elt_name_to_scratch (c))
        goto bail;

    if (consume_char (c, '='))
	add_elt_name = FcTrue;

    e = FcPatternObjectFindElt (pat,
				FcObjectFromName ((const char *) c->scratch));
    if (e)
    {
	FcValueListPtr l;

	if (add_colon)
	    FcStrBufChar (buf, ':');
	if (add_elt_name)
	{
	    FcStrBufString (buf, c->scratch);
	    FcStrBufChar (buf, '=');
	}

	l = FcPatternEltValues(e);
	FcNameUnparseValueList (buf, l, '\0');
    }

filter:
    /* handle filters, if any */
    /* XXX */

    /* align to width */
    if (!buf->failed)
    {
	int after, len;

	after = buf->len;

	len = after - before;

	if (len < -width)
	{
	    /* left align */
	    while (len++ < -width)
		FcStrBufChar (buf, ' ');
	}
	else if (len < width)
	{
	    /* right align */
	    while (len++ < width)
		FcStrBufChar (buf, ' ');
	    len = after - before;
	    memmove (buf->buf + buf->len - len,
		     buf->buf + buf->len - width,
		     len);
	    memset (buf->buf + buf->len - width,
		    ' ',
		    width - len);
	}
    }

    expect_char (c, '}');

bail:
    if (subpat != pat)
	FcPatternDestroy (subpat);
}

static char escaped_char(const char ch)
{
    switch (ch) {
    case 'a':   return '\a';
    case 'b':   return '\b';
    case 'f':   return '\f';
    case 'n':   return '\n';
    case 'r':   return '\r';
    case 't':   return '\t';
    case 'v':   return '\v';
    default:    return ch;
    }
}

static void
interpret (FcFormatContext *c,
	   FcPattern       *pat,
	   FcStrBuf        *buf,
	   FcChar8          term)
{
    for (; *c->format && *c->format != term;)
    {
	switch (*c->format)
	{
	case '\\':
	    c->format++; /* skip over '\\' */
	    if (*c->format)
		FcStrBufChar (buf, escaped_char (*c->format++));
	    continue;
	case '%':
	    interpret_percent (c, pat, buf);
	    continue;
	}
	FcStrBufChar (buf, *c->format++);
    }
}

FcChar8 *
FcPatternFormat (FcPattern *pat, const FcChar8 *format)
{
    FcStrBuf buf;
    FcFormatContext c;

    FcStrBufInit (&buf, 0, 0);
    FcFormatContextInit (&c, format);

    interpret (&c, pat, &buf, '\0');

    FcFormatContextDone (&c);
    return FcStrBufDone (&buf);
}

#define __fcformat__
#include "fcaliastail.h"
#undef __fcformat__