/src/mupdf/source/html/css-parse.c

Source
// Copyright (C) 2004-2025 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
//
// Alternative licensing terms are available from the licensor.
// For commercial licensing, see <https://www.artifex.com/> or contact
// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
// CA 94129, USA, for further information.

#include "mupdf/fitz.h"
#include "html-imp.h"

#include <string.h>

#include "css-properties.h"

struct lexbuf
{
  fz_context *ctx;
  fz_pool *pool;
  const unsigned char *start;
  const unsigned char *s;
  const char *file;
  int line;
  int nest;
  int lookahead;
  int c;
  int string_len;
  char string[1024];
};

static fz_css_value *parse_expr(struct lexbuf *buf);
static fz_css_selector *parse_selector(struct lexbuf *buf);

FZ_NORETURN static void fz_css_error(struct lexbuf *buf, const char *msg)
{
#define PRE_POST_SIZE 30
  unsigned char text[PRE_POST_SIZE * 2 + 4];
  unsigned char *d = text;
  const unsigned char *s = buf->start;
  int n;

  /* We want to make a helpful fragment for the error message.
   * We want err_pos to be the point at which we just tripped
   * the error. err_pos needs to be at least 1 byte behind
   * our read pointer, as we've read that char. */
  const unsigned char *err_pos = buf->s;
  n = 1;

  /* And if we're using lookahead, it's further behind. */
  if (buf->lookahead >= CSS_KEYWORD)
    n += buf->string_len;
  else if (buf->lookahead != EOF)
    n += 1;

  /* But it can't be before the start of the buffer */
  n = fz_mini(n, err_pos - buf->start);
  err_pos -= n;

  /* We're going to try to output:
   * <section prior to the error> ">" <the char that tripped> "<" <section after the error>
   */
  /* Is the section prior to the error too long? If so, truncate it with an ellipsis. */
  n = sizeof(text)-1;
  if (err_pos - s > n-PRE_POST_SIZE - 3)
  {
    *d++ = '.';
    *d++ = '.';
    *d++ = '.';
    n -= 3;
    s = err_pos - (n-PRE_POST_SIZE - 3);
  }

  /* Copy the prefix (if there is one) */
  if (err_pos > s)
  {
    n = err_pos - s;
    while (n)
    {
      unsigned char c = *s++;
      *d++ = (c < 32 || c > 127) ? ' ' : c;
      n--;
    }
  }

  /* Marker, char, end marker */
  *d++ = '>', n--;
  if (*err_pos)
    *d++ = *err_pos++, n--;
  *d++ = '<', n--;

  /* Postfix */
  n = (int)strlen((const char *)err_pos);
  if (n <= PRE_POST_SIZE)
  {
    while (n > 0)
    {
      unsigned char c = *err_pos++;
      *d++ =  (c < 32 || c > 127) ? ' ' : c;
      n--;
    }
  }
  else
  {
    for (n = PRE_POST_SIZE-3; n > 0; n--)
    {
      unsigned char c = *err_pos++;
      *d++ =  (c < 32 || c > 127) ? ' ' : c;
    }

    *d++ = '.';
    *d++ = '.';
    *d++ = '.';
  }
  *d = 0;

  fz_throw(buf->ctx, FZ_ERROR_SYNTAX, "css syntax error: %s (%s:%d) (%s)", msg, buf->file, buf->line, text);
}

fz_css *fz_new_css(fz_context *ctx)
{
  fz_pool *pool = fz_new_pool(ctx);
  fz_css *css = NULL;

  fz_try(ctx)
  {
    css = fz_pool_alloc(ctx, pool, sizeof *css);
    css->pool = pool;
    css->rule = NULL;
  }
  fz_catch(ctx)
  {
    fz_drop_pool(ctx, pool);
    fz_rethrow(ctx);
  }

  return css;
}

void fz_drop_css(fz_context *ctx, fz_css *css)
{
  if (css)
    fz_drop_pool(ctx, css->pool);
}

static fz_css_rule *fz_new_css_rule(fz_context *ctx, fz_pool *pool, fz_css_selector *selector, fz_css_property *declaration)
{
  fz_css_rule *rule = fz_pool_alloc(ctx, pool, sizeof *rule);
  rule->selector = selector;
  rule->declaration = declaration;
  rule->next = NULL;
  return rule;
}

static fz_css_selector *fz_new_css_selector(fz_context *ctx, fz_pool *pool, const char *name)
{
  fz_css_selector *sel = fz_pool_alloc(ctx, pool, sizeof *sel);
  sel->name = name ? fz_pool_strdup(ctx, pool, name) : NULL;
  sel->combine = 0;
  sel->cond = NULL;
  sel->left = NULL;
  sel->right = NULL;
  sel->next = NULL;
  return sel;
}

static fz_css_condition *fz_new_css_condition(fz_context *ctx, fz_pool *pool, int type, const char *key, const char *val)
{
  fz_css_condition *cond = fz_pool_alloc(ctx, pool, sizeof *cond);
  cond->type = type;
  cond->key = key ? fz_pool_strdup(ctx, pool, key) : NULL;
  cond->val = val ? fz_pool_strdup(ctx, pool, val) : NULL;
  cond->next = NULL;
  return cond;
}

static fz_css_property *fz_new_css_property(fz_context *ctx, fz_pool *pool, const char *name, fz_css_value *value, int spec)
{
  struct css_property_info *info = css_property_lookup(name, strlen(name));
  if (info)
  {
    fz_css_property *prop = fz_pool_alloc(ctx, pool, sizeof *prop);
    prop->name = info->key;
    prop->value = value;
    prop->spec = spec;
    prop->important = 0;
    prop->next = NULL;
    return prop;
  }
  return NULL;
}

static fz_css_value *fz_new_css_value_x(fz_context *ctx, fz_pool *pool, int type)
{
  fz_css_value *val = fz_pool_alloc(ctx, pool, sizeof *val);
  val->type = type;
  val->data = NULL;
  val->args = NULL;
  val->next = NULL;
  return val;
}

static fz_css_value *fz_new_css_value(fz_context *ctx, fz_pool *pool, int type, const char *data)
{
  fz_css_value *val = fz_pool_alloc(ctx, pool, sizeof *val);
  val->type = type;
  val->data = fz_pool_strdup(ctx, pool, data);
  val->args = NULL;
  val->next = NULL;
  return val;
}

static void css_lex_next(struct lexbuf *buf)
{
  if (buf->c == 0)
    return;
  buf->s += fz_chartorune(&buf->c, (const char *)buf->s);
  if (buf->c == '{')
    ++buf->nest;
  else if (buf->c == '}')
    --buf->nest;
  else if (buf->c == '\n')
    ++buf->line;
  buf->lookahead = EOF;
}

static void css_lex_init(fz_context *ctx, struct lexbuf *buf, fz_pool *pool, const char *s, const char *file)
{
  buf->ctx = ctx;
  buf->pool = pool;
  buf->s = (const unsigned char *)s;
  buf->lookahead = EOF;
  buf->start = buf->s;
  buf->c = -1;
  buf->file = file;
  buf->line = 1;
  buf->nest = 0;
  css_lex_next(buf);

  buf->string_len = 0;
}

static inline int iswhite(int c)
{
  return c == ' ' || c == '\t' || c == '\r' || c == '\n' || c == '\f';
}

static int isnmstart(int c)
{
  return c == '\\' || c == '_' || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
    (c >= 128 && c <= UCS_MAX);
}

static int isnmchar(int c)
{
  return c == '\\' || c == '_' || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
    (c >= '0' && c <= '9') || c == '-' || (c >= 128 && c <= UCS_MAX);
}

static void css_push_char(struct lexbuf *buf, int c)
{
  char out[4];
  int n = fz_runetochar(out, c);
  if (buf->string_len + n >= (int)nelem(buf->string))
    fz_css_error(buf, "token too long");
  memcpy(buf->string + buf->string_len, out, n);
  buf->string_len += n;
}

static void css_push_zero(struct lexbuf *buf)
{
  if (buf->string_len + 1 >= (int)nelem(buf->string))
    fz_css_error(buf, "token too long");
  buf->string[buf->string_len] = 0;
  buf->string_len += 1;
}

static int css_lex_accept(struct lexbuf *buf, int t)
{
  if (buf->c == t)
  {
    css_lex_next(buf);
    return 1;
  }
  return 0;
}

static void css_lex_expect(struct lexbuf *buf, int t)
{
  if (!css_lex_accept(buf, t))
    fz_css_error(buf, "unexpected character");
}

static int css_lex_number(struct lexbuf *buf)
{
  while (buf->c >= '0' && buf->c <= '9')
  {
    css_push_char(buf, buf->c);
    css_lex_next(buf);
  }

  if (css_lex_accept(buf, '.'))
  {
    css_push_char(buf, '.');
    while (buf->c >= '0' && buf->c <= '9')
    {
      css_push_char(buf, buf->c);
      css_lex_next(buf);
    }
  }

  if (css_lex_accept(buf, '%'))
  {
    css_push_char(buf, '%');
    css_push_zero(buf);
    return CSS_PERCENT;
  }

  if (isnmstart(buf->c))
  {
    css_push_char(buf, buf->c);
    css_lex_next(buf);
    while (isnmchar(buf->c))
    {
      css_push_char(buf, buf->c);
      css_lex_next(buf);
    }
    css_push_zero(buf);
    return CSS_LENGTH;
  }

  css_push_zero(buf);
  return CSS_NUMBER;
}

static int css_lex_keyword(struct lexbuf *buf)
{
  while (isnmchar(buf->c))
  {
    css_push_char(buf, buf->c);
    css_lex_next(buf);
  }
  css_push_zero(buf);
  return CSS_KEYWORD;
}

static int css_lex_hash(struct lexbuf *buf)
{
  while (isnmchar(buf->c))
  {
    css_push_char(buf, buf->c);
    css_lex_next(buf);
  }
  css_push_zero(buf);
  return CSS_HASH;
}

static int css_lex_string(struct lexbuf *buf, int q)
{
  while (buf->c && buf->c != q)
  {
    if (css_lex_accept(buf, '\\'))
    {
      if (css_lex_accept(buf, 'n'))
        css_push_char(buf, '\n');
      else if (css_lex_accept(buf, 'r'))
        css_push_char(buf, '\r');
      else if (css_lex_accept(buf, 'f'))
        css_push_char(buf, '\f');
      else if (css_lex_accept(buf, '\f'))
        /* line continuation */ ;
      else if (css_lex_accept(buf, '\n'))
        /* line continuation */ ;
      else if (css_lex_accept(buf, '\r'))
        css_lex_accept(buf, '\n');
      else
      {
        css_push_char(buf, buf->c);
        css_lex_next(buf);
      }
    }
    else
    {
      css_push_char(buf, buf->c);
      css_lex_next(buf);
    }
  }
  css_lex_expect(buf, q);
  css_push_zero(buf);
  return CSS_STRING;
}

static void css_lex_uri(struct lexbuf *buf)
{
  while (buf->c && buf->c != ')' && !iswhite(buf->c))
  {
    if (css_lex_accept(buf, '\\'))
    {
      if (css_lex_accept(buf, 'n'))
        css_push_char(buf, '\n');
      else if (css_lex_accept(buf, 'r'))
        css_push_char(buf, '\r');
      else if (css_lex_accept(buf, 'f'))
        css_push_char(buf, '\f');
      else
      {
        css_push_char(buf, buf->c);
        css_lex_next(buf);
      }
    }
    else if (buf->c == '!' || buf->c == '#' || buf->c == '$' || buf->c == '%' || buf->c == '&' ||
        (buf->c >= '*' && buf->c <= '[') ||
        (buf->c >= ']' && buf->c <= '~') ||
        buf->c > 159)
    {
      css_push_char(buf, buf->c);
      css_lex_next(buf);
    }
    else
      fz_css_error(buf, "unexpected character in url");
  }
  css_push_zero(buf);
}

static int css_lex(struct lexbuf *buf)
{
  int t;

  // TODO: keyword escape sequences

  buf->string_len = 0;

restart:
  if (buf->c == 0)
    return EOF;

  if (iswhite(buf->c))
  {
    while (iswhite(buf->c))
      css_lex_next(buf);
    return ' ';
  }

  if (css_lex_accept(buf, '/'))
  {
    if (css_lex_accept(buf, '*'))
    {
      while (buf->c)
      {
        if (css_lex_accept(buf, '*'))
        {
          while (buf->c == '*')
            css_lex_next(buf);
          if (css_lex_accept(buf, '/'))
            goto restart;
        }
        css_lex_next(buf);
      }
      fz_css_error(buf, "unterminated comment");
    }
    return '/';
  }

  if (css_lex_accept(buf, '<'))
  {
    if (css_lex_accept(buf, '!'))
    {
      css_lex_expect(buf, '-');
      css_lex_expect(buf, '-');
      goto restart; /* ignore CDO */
    }
    return '<';
  }

  if (css_lex_accept(buf, '-'))
  {
    if (css_lex_accept(buf, '-'))
    {
      if (css_lex_accept(buf, '>'))
        goto restart; /* ignore CDC */
    }
    if (isnmstart(buf->c))
    {
      css_push_char(buf, '-');
      return css_lex_keyword(buf);
    }
    return '-';
  }

  if (css_lex_accept(buf, '.'))
  {
    if (buf->c >= '0' && buf->c <= '9')
    {
      css_push_char(buf, '.');
      return css_lex_number(buf);
    }
    return '.';
  }

  if (css_lex_accept(buf, '#'))
  {
    if (isnmchar(buf->c))
      return css_lex_hash(buf);
    return '#';
  }

  if (css_lex_accept(buf, '"'))
    return css_lex_string(buf, '"');
  if (css_lex_accept(buf, '\''))
    return css_lex_string(buf, '\'');

  if (buf->c >= '0' && buf->c <= '9')
    return css_lex_number(buf);

  if (css_lex_accept(buf, 'u'))
  {
    if (css_lex_accept(buf, 'r'))
    {
      if (css_lex_accept(buf, 'l'))
      {
        if (css_lex_accept(buf, '('))
        {
          while (iswhite(buf->c))
            css_lex_next(buf);
          if (css_lex_accept(buf, '"'))
            css_lex_string(buf, '"');
          else if (css_lex_accept(buf, '\''))
            css_lex_string(buf, '\'');
          else
            css_lex_uri(buf);
          while (iswhite(buf->c))
            css_lex_next(buf);
          css_lex_expect(buf, ')');
          return CSS_URI;
        }
        css_push_char(buf, 'u');
        css_push_char(buf, 'r');
        css_push_char(buf, 'l');
        return css_lex_keyword(buf);
      }
      css_push_char(buf, 'u');
      css_push_char(buf, 'r');
      return css_lex_keyword(buf);
    }
    css_push_char(buf, 'u');
    return css_lex_keyword(buf);
  }

  if (isnmstart(buf->c))
  {
    css_push_char(buf, buf->c);
    css_lex_next(buf);
    return css_lex_keyword(buf);
  }

  t = buf->c;
  css_lex_next(buf);
  return t;
}

static void next(struct lexbuf *buf)
{
  buf->lookahead = css_lex(buf);
}

static int accept(struct lexbuf *buf, int t)
{
  if (buf->lookahead == t)
  {
    next(buf);
    return 1;
  }
  return 0;
}

static void expect(struct lexbuf *buf, int t)
{
  if (accept(buf, t))
    return;
  fz_css_error(buf, "unexpected token");
}

static void white(struct lexbuf *buf)
{
  while (buf->lookahead == ' ')
    next(buf);
}

static int iscond(int t)
{
  return t == ':' || t == '.' || t == '[' || t == CSS_HASH;
}

static fz_css_value *parse_term(struct lexbuf *buf)
{
  fz_css_value *v;

  if (buf->lookahead == '+' || buf->lookahead == '-')
  {
    float sign = buf->lookahead == '-' ? -1 : 1;
    next(buf);
    if (buf->lookahead != CSS_NUMBER && buf->lookahead != CSS_LENGTH && buf->lookahead != CSS_PERCENT)
      fz_css_error(buf, "expected number");
    if (sign < 0)
    {
      v = fz_new_css_value_x(buf->ctx, buf->pool, buf->lookahead);
      v->data = fz_pool_alloc(buf->ctx, buf->pool, strlen(buf->string) + 2);
      v->data[0] = '-';
      strcpy(v->data + 1, buf->string);
    }
    else
    {
      v = fz_new_css_value(buf->ctx, buf->pool, buf->lookahead, buf->string);
    }
    next(buf);
    white(buf);
    return v;
  }

  if (buf->lookahead == CSS_KEYWORD)
  {
    v = fz_new_css_value(buf->ctx, buf->pool, CSS_KEYWORD, buf->string);
    next(buf);
    if (accept(buf, '('))
    {
      white(buf);
      v->type = '(';
      v->args = parse_expr(buf);
      expect(buf, ')');
    }
    white(buf);
    return v;
  }

  switch (buf->lookahead)
  {
  case CSS_HASH:
  case CSS_STRING:
  case CSS_URI:
  case CSS_NUMBER:
  case CSS_LENGTH:
  case CSS_PERCENT:
    v = fz_new_css_value(buf->ctx, buf->pool, buf->lookahead, buf->string);
    next(buf);
    white(buf);
    return v;
  }

  fz_css_error(buf, "expected value");
}

static fz_css_value *parse_expr(struct lexbuf *buf)
{
  fz_css_value *head, *tail;

  head = tail = parse_term(buf);

  while (buf->lookahead != '}' && buf->lookahead != ';' && buf->lookahead != '!' &&
      buf->lookahead != ')' && buf->lookahead != EOF)
  {
    if (accept(buf, ','))
    {
      white(buf);
      if (buf->lookahead != ';')
      {
        tail = tail->next = fz_new_css_value(buf->ctx, buf->pool, ',', ",");
        tail = tail->next = parse_term(buf);
      }
    }
    else if (accept(buf, '/'))
    {
      white(buf);
      tail = tail->next = fz_new_css_value(buf->ctx, buf->pool, '/', "/");
      tail = tail->next = parse_term(buf);
    }
    else
    {
      tail = tail->next = parse_term(buf);
    }
  }

  return head;
}

static fz_css_property *parse_declaration(struct lexbuf *buf)
{
  fz_css_property *p;

  if (buf->lookahead != CSS_KEYWORD)
    fz_css_error(buf, "expected keyword in property");
  p = fz_new_css_property(buf->ctx, buf->pool, buf->string, NULL, 0);
  next(buf);

  white(buf);
  expect(buf, ':');
  white(buf);

  if (p)
    p->value = parse_expr(buf);
  else
    (void) parse_expr(buf);

  /* !important */
  if (accept(buf, '!'))
  {
    white(buf);
    if (buf->lookahead != CSS_KEYWORD || strcmp(buf->string, "important"))
      fz_css_error(buf, "expected keyword 'important' after '!'");
    if (p)
      p->important = 1;
    next(buf);
    white(buf);
  }

  return p;
}

static fz_css_property *parse_declaration_list(struct lexbuf *buf)
{
  fz_css_property *head, *tail = NULL, *p;

  white(buf);

  if (buf->lookahead == '}' || buf->lookahead == EOF)
    return NULL;

  p = parse_declaration(buf);
  if (p)
    tail = p;
  head = tail;

  while (accept(buf, ';'))
  {
    white(buf);

    if (buf->lookahead != '}' && buf->lookahead != ';' && buf->lookahead != EOF)
    {
      p = parse_declaration(buf);
      if (p)
      {
        if (!head)
          head = tail = p;
        else
          tail = tail->next = p;
      }
    }
  }

  return head;
}

static char *parse_attrib_value(struct lexbuf *buf)
{
  char *s;

  if (buf->lookahead == CSS_KEYWORD || buf->lookahead == CSS_STRING)
  {
    s = fz_pool_strdup(buf->ctx, buf->pool, buf->string);
    next(buf);
    white(buf);
    return s;
  }

  fz_css_error(buf, "expected attribute value");
}

static char *css_lex_pseudo_expr(struct lexbuf *buf)
{
  buf->string_len = 0;
  for (;;)
  {
    if (buf->c == 0)
      return NULL;
    if (css_lex_accept(buf, ')'))
    {
      css_push_zero(buf);
      return fz_pool_strdup(buf->ctx, buf->pool, buf->string);
    }
    css_push_char(buf, buf->c);
    css_lex_next(buf);
  }
}

static fz_css_condition *parse_condition(struct lexbuf *buf)
{
  fz_css_condition *c;

  if (accept(buf, ':'))
  {
    (void)accept(buf, ':'); /* swallow css3 :: syntax and pretend it's a normal pseudo-class */
    if (buf->lookahead != CSS_KEYWORD)
      fz_css_error(buf, "expected keyword after ':'");
    c = fz_new_css_condition(buf->ctx, buf->pool, ':', buf->string, NULL);
    next(buf);

    // TODO -- parse :is, :not, :where, :has logical combinations with selector list as argument

    if (buf->lookahead == '(')
    {
      c->val = css_lex_pseudo_expr(buf);
      next(buf);
    }
    return c;
  }

  if (accept(buf, '.'))
  {
    if (buf->lookahead != CSS_KEYWORD)
      fz_css_error(buf, "expected keyword after '.'");
    c = fz_new_css_condition(buf->ctx, buf->pool, '.', "class", buf->string);
    next(buf);
    return c;
  }

  if (accept(buf, '['))
  {
    white(buf);

    if (buf->lookahead != CSS_KEYWORD)
      fz_css_error(buf, "expected keyword after '['");
    c = fz_new_css_condition(buf->ctx, buf->pool, '[', buf->string, NULL);
    next(buf);

    white(buf);

    if (accept(buf, '='))
    {
      c->type = '=';
      c->val = parse_attrib_value(buf);
    }
    else if (accept(buf, '|'))
    {
      expect(buf, '=');
      c->type = '|';
      c->val = parse_attrib_value(buf);
    }
    else if (accept(buf, '~'))
    {
      expect(buf, '=');
      c->type = '~';
      c->val = parse_attrib_value(buf);
    }

    expect(buf, ']');

    return c;
  }

  if (buf->lookahead == CSS_HASH)
  {
    c = fz_new_css_condition(buf->ctx, buf->pool, '#', "id", buf->string);
    next(buf);
    return c;
  }

  fz_css_error(buf, "expected condition");
}

static fz_css_condition *parse_condition_list(struct lexbuf *buf)
{
  fz_css_condition *head, *tail;

  head = tail = parse_condition(buf);
  while (iscond(buf->lookahead))
  {
    tail = tail->next = parse_condition(buf);
  }
  return head;
}

static fz_css_selector *parse_simple_selector(struct lexbuf *buf)
{
  fz_css_selector *s;

  if (accept(buf, '*'))
  {
    s = fz_new_css_selector(buf->ctx, buf->pool, NULL);
    if (iscond(buf->lookahead))
      s->cond = parse_condition_list(buf);
    return s;
  }
  else if (buf->lookahead == CSS_KEYWORD)
  {
    s = fz_new_css_selector(buf->ctx, buf->pool, buf->string);
    next(buf);
    if (iscond(buf->lookahead))
      s->cond = parse_condition_list(buf);
    return s;
  }
  else if (iscond(buf->lookahead))
  {
    s = fz_new_css_selector(buf->ctx, buf->pool, NULL);
    s->cond = parse_condition_list(buf);
    return s;
  }

  fz_css_error(buf, "expected selector");
}

static fz_css_selector *parse_combinator(struct lexbuf *buf, int c, fz_css_selector *a)
{
  fz_css_selector *sel, *b;
  white(buf);
  b = parse_simple_selector(buf);
  sel = fz_new_css_selector(buf->ctx, buf->pool, NULL);
  sel->combine = c;
  sel->left = a;
  sel->right = b;
  return sel;
}

static fz_css_selector *parse_selector(struct lexbuf *buf)
{
  fz_css_selector *sel = parse_simple_selector(buf);
  for (;;)
  {
    if (accept(buf, ' '))
    {
      white(buf);
      if (accept(buf, '+'))
        sel = parse_combinator(buf, '+', sel);
      else if (accept(buf, '>'))
        sel = parse_combinator(buf, '>', sel);
      else if (buf->lookahead != ',' && buf->lookahead != '{' && buf->lookahead != EOF)
        sel = parse_combinator(buf, ' ', sel);
      else
        break;
    }
    else if (accept(buf, '+'))
      sel = parse_combinator(buf, '+', sel);
    else if (accept(buf, '>'))
      sel = parse_combinator(buf, '>', sel);
    else
      break;
  }
  return sel;
}

static fz_css_selector *parse_selector_list(struct lexbuf *buf)
{
  fz_css_selector *head, *tail;

  head = tail = parse_selector(buf);
  while (accept(buf, ','))
  {
    white(buf);
    tail = tail->next = parse_selector(buf);
  }
  return head;
}

static void parse_recover(struct lexbuf *buf)
{
  fz_rethrow_unless(buf->ctx, FZ_ERROR_SYNTAX);
  fz_report_error(buf->ctx);
  while (buf->lookahead != EOF)
  {
    if (accept(buf, '}') && buf->nest <= 0)
    {
      buf->nest = 0;
      white(buf);
      break;
    }
    next(buf);
  }
}

static fz_css_rule *parse_ruleset(struct lexbuf *buf)
{
  fz_css_selector *s = NULL;
  fz_css_property *p = NULL;

  fz_try(buf->ctx)
  {
    s = parse_selector_list(buf);
    expect(buf, '{');
    p = parse_declaration_list(buf);
    expect(buf, '}');
    white(buf);
  }
  fz_catch(buf->ctx)
  {
    parse_recover(buf);
    return NULL;
  }

  return fz_new_css_rule(buf->ctx, buf->pool, s, p);
}

static fz_css_rule *parse_at_page(struct lexbuf *buf)
{
  fz_css_selector *s = NULL;
  fz_css_property *p = NULL;

  fz_try(buf->ctx)
  {
    white(buf);
    if (accept(buf, ':'))
    {
      expect(buf, CSS_KEYWORD);
      white(buf);
    }
    expect(buf, '{');
    p = parse_declaration_list(buf);
    expect(buf, '}');
    white(buf);
  }
  fz_catch(buf->ctx)
  {
    parse_recover(buf);
    return NULL;
  }

  s = fz_new_css_selector(buf->ctx, buf->pool, "@page");
  return fz_new_css_rule(buf->ctx, buf->pool, s, p);
}

static fz_css_rule *parse_at_font_face(struct lexbuf *buf)
{
  fz_css_selector *s = NULL;
  fz_css_property *p = NULL;

  fz_try(buf->ctx)
  {
    white(buf);
    expect(buf, '{');
    p = parse_declaration_list(buf);
    expect(buf, '}');
    white(buf);
  }
  fz_catch(buf->ctx)
  {
    parse_recover(buf);
    return NULL;
  }

  s = fz_new_css_selector(buf->ctx, buf->pool, "@font-face");
  return fz_new_css_rule(buf->ctx, buf->pool, s, p);
}

static void parse_at_rule(struct lexbuf *buf)
{
  expect(buf, CSS_KEYWORD);

  /* skip until '{' or ';' */
  while (buf->lookahead != EOF)
  {
    if (accept(buf, ';'))
    {
      white(buf);
      return;
    }
    if (accept(buf, '{'))
    {
      int depth = 1;
      while (buf->lookahead != EOF && depth > 0)
      {
        if (accept(buf, '{'))
          ++depth;
        else if (accept(buf, '}'))
          --depth;
        else
          next(buf);
      }
      white(buf);
      return;
    }
    next(buf);
  }
}

static fz_css_rule *parse_stylesheet(struct lexbuf *buf, fz_css_rule *chain)
{
  fz_css_rule *rule, **nextp, *tail, *x;

  tail = chain;
  if (tail)
  {
    while (tail->next)
      tail = tail->next;
    nextp = &tail->next;
  }
  else
  {
    nextp = &tail;
  }

  white(buf);

  while (buf->lookahead != EOF)
  {
    if (accept(buf, '@'))
    {
      if (buf->lookahead == CSS_KEYWORD && !strcmp(buf->string, "page"))
      {
        next(buf);
        x = parse_at_page(buf);
        if (x)
        {
          rule = *nextp = x;
          nextp = &rule->next;
        }
      }
      else if (buf->lookahead == CSS_KEYWORD && !strcmp(buf->string, "font-face"))
      {
        next(buf);
        x = parse_at_font_face(buf);
        if (x)
        {
          rule = *nextp = x;
          nextp = &rule->next;
        }
      }
      else
      {
        parse_at_rule(buf);
      }
    }
    else
    {
      x = parse_ruleset(buf);
      if (x)
      {
        rule = *nextp = x;
        nextp = &rule->next;
      }
    }
    white(buf);
  }

  return chain ? chain : tail;
}

const char *fz_css_property_name(int key)
{
  const char *name = "unknown";
  size_t i;
  for (i = 0; i < nelem(css_property_list); ++i)
    if (*css_property_list[i].name && css_property_list[i].key == key)
      name = css_property_list[i].name;
  return name;
}

fz_css_property *fz_parse_css_properties(fz_context *ctx, fz_pool *pool, const char *source)
{
  struct lexbuf buf;
  css_lex_init(ctx, &buf, pool, source, "<inline>");
  next(&buf);
  return parse_declaration_list(&buf);
}

void fz_parse_css(fz_context *ctx, fz_css *css, const char *source, const char *file)
{
  struct lexbuf buf;
  css_lex_init(ctx, &buf, css->pool, source, file);
  next(&buf);
  css->rule = parse_stylesheet(&buf, css->rule);
}

Coverage Report

Created: 2025-11-07 06:58