/* Low-level bidirectional buffer/string-scanning functions for GNU Emacs.
- Copyright (C) 2000-2001, 2004-2005, 2009-2012
- Free Software Foundation, Inc.
+ Copyright (C) 2000-2001, 2004-2005, 2009-2014 Free Software
+ Foundation, Inc.
This file is part of GNU Emacs.
A sequential implementation of the Unicode Bidirectional algorithm,
(UBA) as per UAX#9, a part of the Unicode Standard.
- Unlike the reference and most other implementations, this one is
- designed to be called once for every character in the buffer or
- string.
+ Unlike the Reference Implementation and most other implementations,
+ this one is designed to be called once for every character in the
+ buffer or string. That way, we can leave intact the design of the
+ Emacs display engine, whereby an iterator object is used to
+ traverse buffer or string text character by character, and generate
+ the necessary data for displaying each character in 'struct glyph'
+ objects. (See xdisp.c for the details of that iteration.) The
+ functions on this file replace the original linear iteration in the
+ logical order of the text with a non-linear iteration in the visual
+ order, i.e. in the order characters should be shown on display.
The main entry point is bidi_move_to_visually_next. Each time it
is called, it finds the next character in the visual order, and
A note about references to UAX#9 rules: if the reference says
something like "X9/Retaining", it means that you need to refer to
rule X9 and to its modifications described in the "Implementation
- Notes" section of UAX#9, under "Retaining Format Codes". */
+ Notes" section of UAX#9, under "Retaining Format Codes".
+
+ Here's the overview of the design of the reordering engine
+ implemented by this file.
+
+ Basic implementation structure
+ ------------------------------
+
+ The sequential processing steps described by UAX#9 are implemented
+ as recursive levels of processing, all of which examine the next
+ character in the logical order. This hierarchy of processing looks
+ as follows, from the innermost (deepest) to the outermost level,
+ omitting some subroutines used by each level:
+
+ bidi_fetch_char -- fetch next character
+ bidi_resolve_explicit -- resolve explicit levels and directions
+ bidi_resolve_weak -- resolve weak types
+ bidi_resolve_neutral -- resolve neutral types
+ bidi_level_of_next_char -- resolve implicit levels
+
+ Each level calls the level below it, and works on the result
+ returned by the lower level, including all of its sub-levels.
+
+ Unlike all the levels below it, bidi_level_of_next_char can return
+ the information about either the next or previous character in the
+ logical order, depending on the current direction of scanning the
+ buffer or string. For the next character, it calls all the levels
+ below it; for the previous character, it uses the cache, described
+ below.
+
+ Thus, the result of calling bidi_level_of_next_char is the resolved
+ level of the next or the previous character in the logical order.
+ Based on this information, the function bidi_move_to_visually_next
+ finds the next character in the visual order and updates the
+ direction in which the buffer is scanned, either forward or
+ backward, to find the next character to be displayed. (Text is
+ scanned backwards when it needs to be reversed for display, i.e. if
+ the visual order is the inverse of the logical order.) This
+ implements the last, reordering steps of the UBA, by successively
+ calling bidi_level_of_next_char until the character of the required
+ embedding level is found; the scan direction is dynamically updated
+ as a side effect. See the commentary before the 'while' loop in
+ bidi_move_to_visually_next, for the details.
+
+ Fetching characters
+ -------------------
+
+ In a nutshell, fetching the next character boils down to calling
+ STRING_CHAR_AND_LENGTH, passing it the address of a buffer or
+ string position. See bidi_fetch_char. However, if the next
+ character is "covered" by a display property of some kind,
+ bidi_fetch_char returns the u+FFFC "object replacement character"
+ that represents the entire run of text covered by the display
+ property. (The ch_len and nchars members of 'struct bidi_it'
+ reflect the length in bytes and characters of that text.) This is
+ so we reorder text on both sides of the display property as
+ appropriate for an image or embedded string. Similarly, text
+ covered by a display spec of the form '(space ...)', is replaced
+ with the u+2029 paragraph separator character, so such display
+ specs produce the same effect as a TAB under UBA. Both these
+ special characters are not actually displayed -- the display
+ property is displayed instead -- but just used to compute the
+ embedding level of the surrounding text so as to produce the
+ required effect.
+
+ Bidi iterator states
+ --------------------
+
+ The UBA is highly context dependent in some of its parts,
+ i.e. results of processing a character can generally depend on
+ characters very far away. The UAX#9 description of the UBA
+ prescribes a stateful processing of each character, whereby the
+ results of this processing depend on various state variables, such
+ as the current embedding level, level stack, and directional
+ override status. In addition, the UAX#9 description includes many
+ passages like this (from rule W2 in this case):
+
+ Search backward from each instance of a European number until the
+ first strong type (R, L, AL, or sos) is found. If an AL is found,
+ change the type of the European number to Arabic number.
+
+ To support this, we use a bidi iterator object, 'struct bidi_it',
+ which is a sub-structure of 'struct it' used by xdisp.c (see
+ dispextern.h for the definition of both of these structures). The
+ bidi iterator holds the entire state of the iteration required by
+ the UBA, and is updated as the text is traversed. In particular,
+ the embedding level of the current character being resolved is
+ recorded in the iterator state. To avoid costly searches backward
+ in support of rules like W2 above, the necessary character types
+ are also recorded in the iterator state as they are found during
+ the forward scan, and then used when such rules need to be applied.
+ (Forward scans cannot be avoided in this way; they need to be
+ performed at least once, and the results recorded in the iterator
+ state, to be reused until the forward scan oversteps the recorded
+ position.)
+
+ In this manner, the iterator state acts as a mini-cache of
+ contextual information required for resolving the level of the
+ current character by various UBA rules.
+
+ Caching of bidi iterator states
+ -------------------------------
+
+ As described above, the reordering engine uses the information
+ recorded in the bidi iterator state in order to resolve the
+ embedding level of the current character. When the reordering
+ engine needs to process the next character in the logical order, it
+ fetches it and applies to it all the UBA levels, updating the
+ iterator state as it goes. But when the buffer or string is
+ scanned backwards, i.e. in the reverse order of buffer/string
+ positions, the scanned characters were already processed during the
+ preceding forward scan (see bidi_find_other_level_edge). To avoid
+ costly re-processing of characters that were already processed
+ during the forward scan, the iterator states computed while
+ scanning forward are cached.
+
+ The cache is just a linear array of 'struct bidi_it' objects, which
+ is dynamically allocated and reallocated as needed, since the size
+ of the cache depends on the text being processed. We only need the
+ cache while processing embedded levels higher than the base
+ paragraph embedding level, because these higher levels require
+ changes in scan direction. Therefore, as soon as we are back to
+ the base embedding level, we can free the cache; see the calls to
+ bidi_cache_reset and bidi_cache_shrink, for the conditions to do
+ this.
+
+ The cache maintains the index of the next unused cache slot -- this
+ is where the next iterator state will be cached. The function
+ bidi_cache_iterator_state saves an instance of the state in the
+ cache and increments the unused slot index. The companion function
+ bidi_cache_find looks up a cached state that corresponds to a given
+ buffer/string position. All of the cached states must correspond
+ 1:1 to the buffer or string region whose processing they reflect;
+ bidi.c will abort if it finds cache slots that violate this 1:1
+ correspondence.
+
+ When the parent iterator 'struct it' is pushed (see push_it in
+ xdisp.c) to pause the current iteration and start iterating over a
+ different object (e.g., a 'display' string that covers some buffer
+ text), the bidi iterator cache needs to be "pushed" as well, so
+ that a new empty cache could be used while iterating over the new
+ object. Later, when the new object is exhausted, and xdisp.c calls
+ pop_it, we need to "pop" the bidi cache as well and return to the
+ original cache. See bidi_push_it and bidi_pop_it for how this is
+ done.
+
+ Some functions of the display engine save copies of 'struct it' in
+ local variables, and restore them later. For examples, see
+ pos_visible_p and move_it_in_display_line_to in xdisp.c, and
+ window_scroll_pixel_based in window.c. When this happens, we need
+ to save and restore the bidi cache as well, because conceptually
+ the cache is part of the 'struct it' state, and needs to be in
+ perfect sync with the portion of the buffer/string that is being
+ processed. This saving and restoring of the cache state is handled
+ by bidi_shelve_cache and bidi_unshelve_cache, and the helper macros
+ SAVE_IT and RESTORE_IT defined on xdisp.c.
+
+ Note that, because reordering is implemented below the level in
+ xdisp.c that breaks glyphs into screen lines, we are violating
+ paragraph 3.4 of UAX#9. which mandates that line breaking shall be
+ done before reordering each screen line separately. However,
+ following UAX#9 to the letter in this matter goes against the basic
+ design of the Emacs display engine, and so we choose here this
+ minor deviation from the UBA letter in preference to redesign of
+ the display engine. The effect of this is only seen in continued
+ lines that are broken into screen lines in the middle of a run
+ whose direction is opposite to the paragraph's base direction.
+
+ Important design and implementation note: when the code needs to
+ scan far ahead, be sure to avoid such scans as much as possible
+ when the buffer/string doesn't contain any RTL characters. Users
+ of left-to-right scripts will never forgive you if you introduce
+ some slow-down due to bidi in situations that don't involve any
+ bidirectional text. See the large comment near the beginning of
+ bidi_resolve_neutral, for one situation where such shortcut was
+ necessary. */
#include <config.h>
#include <stdio.h>
-#include <setjmp.h>
#include "lisp.h"
-#include "buffer.h"
#include "character.h"
+#include "buffer.h"
#include "dispextern.h"
+#include "region-cache.h"
-static int bidi_initialized = 0;
+static bool bidi_initialized = 0;
static Lisp_Object bidi_type_table, bidi_mirror_table;
-#define LRM_CHAR 0x200E
-#define RLM_CHAR 0x200F
-#define BIDI_EOB -1
+#define BIDI_EOB (-1)
/* Data type for describing the bidirectional character categories. */
typedef enum {
UNKNOWN_BC,
NEUTRAL,
WEAK,
- STRONG
+ STRONG,
+ EXPLICIT_FORMATTING
} bidi_category_t;
/* UAX#9 says to search only for L, AL, or R types of characters, and
ignore RLE, RLO, LRE, and LRO, when determining the base paragraph
level. Yudit indeed ignores them. This variable is therefore set
- by default to ignore them, but setting it to zero will take them
- into account. */
-extern int bidi_ignore_explicit_marks_for_paragraph_level EXTERNALLY_VISIBLE;
-int bidi_ignore_explicit_marks_for_paragraph_level = 1;
+ by default to ignore them, but clearing it will take them into
+ account. */
+extern bool bidi_ignore_explicit_marks_for_paragraph_level EXTERNALLY_VISIBLE;
+bool bidi_ignore_explicit_marks_for_paragraph_level = 1;
static Lisp_Object paragraph_start_re, paragraph_separate_re;
static Lisp_Object Qparagraph_start, Qparagraph_separate;
/* Return the bidi type of a character CH, subject to the current
directional OVERRIDE. */
-static inline bidi_type_t
+static bidi_type_t
bidi_get_type (int ch, bidi_dir_t override)
{
bidi_type_t default_type;
if (ch == BIDI_EOB)
return NEUTRAL_B;
if (ch < 0 || ch > MAX_CHAR)
- abort ();
+ emacs_abort ();
default_type = (bidi_type_t) XINT (CHAR_TABLE_REF (bidi_type_table, ch));
/* Every valid character code, even those that are unassigned by the
DerivedBidiClass.txt file. Therefore, if we ever get UNKNOWN_BT
(= zero) code from CHAR_TABLE_REF, that's a bug. */
if (default_type == UNKNOWN_BT)
- abort ();
-
- if (override == NEUTRAL_DIR)
- return default_type;
+ emacs_abort ();
switch (default_type)
{
- /* Although UAX#9 does not tell, it doesn't make sense to
- override NEUTRAL_B and LRM/RLM characters. */
+ case WEAK_BN:
case NEUTRAL_B:
case LRE:
case LRO:
case RLO:
case PDF:
return default_type;
+ /* FIXME: The isolate controls are treated as BN until we add
+ support for UBA v6.3. */
+ case LRI:
+ case RLI:
+ case FSI:
+ case PDI:
+ return WEAK_BN;
default:
- switch (ch)
- {
- case LRM_CHAR:
- case RLM_CHAR:
- return default_type;
- default:
- if (override == L2R) /* X6 */
- return STRONG_L;
- else if (override == R2L)
- return STRONG_R;
- else
- abort (); /* can't happen: handled above */
- }
+ if (override == L2R)
+ return STRONG_L;
+ else if (override == R2L)
+ return STRONG_R;
+ else
+ return default_type;
}
}
-static inline void
+static void
bidi_check_type (bidi_type_t type)
{
- xassert (UNKNOWN_BT <= type && type <= NEUTRAL_ON);
+ eassert (UNKNOWN_BT <= type && type <= NEUTRAL_ON);
}
/* Given a bidi TYPE of a character, return its category. */
-static inline bidi_category_t
+static bidi_category_t
bidi_get_category (bidi_type_t type)
{
switch (type)
case STRONG_L:
case STRONG_R:
case STRONG_AL:
- case LRE:
- case LRO:
- case RLE:
- case RLO:
return STRONG;
- case PDF: /* ??? really?? */
case WEAK_EN:
case WEAK_ES:
case WEAK_ET:
case WEAK_CS:
case WEAK_NSM:
case WEAK_BN:
+ /* FIXME */
+ case LRI:
+ case RLI:
+ case FSI:
+ case PDI:
return WEAK;
case NEUTRAL_B:
case NEUTRAL_S:
case NEUTRAL_WS:
case NEUTRAL_ON:
return NEUTRAL;
+ case LRE:
+ case LRO:
+ case RLE:
+ case RLO:
+ case PDF:
+#if 0
+ /* FIXME: This awaits implementation of isolate support. */
+ case LRI:
+ case RLI:
+ case FSI:
+ case PDI:
+#endif
+ return EXPLICIT_FORMATTING;
default:
- abort ();
+ emacs_abort ();
}
}
if (c == BIDI_EOB)
return c;
if (c < 0 || c > MAX_CHAR)
- abort ();
+ emacs_abort ();
val = CHAR_TABLE_REF (bidi_mirror_table, c);
if (INTEGERP (val))
{
- int v = XINT (val);
+ int v;
+ /* When debugging, check before assigning to V, so that the check
+ isn't broken by undefined behavior due to int overflow. */
+ eassert (CHAR_VALID_P (XINT (val)));
+
+ v = XINT (val);
+
+ /* Minimal test we must do in optimized builds, to prevent weird
+ crashes further down the road. */
if (v < 0 || v > MAX_CHAR)
- abort ();
+ emacs_abort ();
return v;
}
embedding levels on either side of the run boundary. Also, update
the saved info about previously seen characters, since that info is
generally valid for a single level run. */
-static inline void
+static void
bidi_set_sor_type (struct bidi_it *bidi_it, int level_before, int level_after)
{
int higher_level = (level_before > level_after ? level_before : level_after);
/* Push the current embedding level and override status; reset the
current level to LEVEL and the current override status to OVERRIDE. */
-static inline void
+static void
bidi_push_embedding_level (struct bidi_it *bidi_it,
int level, bidi_dir_t override)
{
bidi_it->stack_idx++;
- xassert (bidi_it->stack_idx < BIDI_MAXLEVEL);
+ eassert (bidi_it->stack_idx < BIDI_MAXLEVEL);
bidi_it->level_stack[bidi_it->stack_idx].level = level;
bidi_it->level_stack[bidi_it->stack_idx].override = override;
}
/* Pop the embedding level and directional override status from the
stack, and return the new level. */
-static inline int
+static int
bidi_pop_embedding_level (struct bidi_it *bidi_it)
{
/* UAX#9 says to ignore invalid PDFs. */
}
/* Record in SAVED_INFO the information about the current character. */
-static inline void
+static void
bidi_remember_char (struct bidi_saved_info *saved_info,
struct bidi_it *bidi_it)
{
/* Copy the bidi iterator from FROM to TO. To save cycles, this only
copies the part of the level stack that is actually in use. */
-static inline void
+static void
bidi_copy_it (struct bidi_it *to, struct bidi_it *from)
{
- int i;
-
- /* Copy everything except the level stack and beyond. */
- memcpy (to, from, offsetof (struct bidi_it, level_stack[0]));
-
- /* Copy the active part of the level stack. */
- to->level_stack[0] = from->level_stack[0]; /* level zero is always in use */
- for (i = 1; i <= from->stack_idx; i++)
- to->level_stack[i] = from->level_stack[i];
+ /* Copy everything from the start through the active part of
+ the level stack. */
+ memcpy (to, from,
+ (offsetof (struct bidi_it, level_stack[1])
+ + from->stack_idx * sizeof from->level_stack[0]));
}
\f
intact. This is called when the cached information is no more
useful for the current iteration, e.g. when we were reseated to a
new position on the same object. */
-static inline void
+static void
bidi_cache_reset (void)
{
bidi_cache_idx = bidi_cache_start;
iterator for reordering a buffer or a string that does not come
from display properties, because that means all the previously
cached info is of no further use. */
-static inline void
+static void
bidi_cache_shrink (void)
{
if (bidi_cache_size > BIDI_CACHE_CHUNK)
{
- bidi_cache
- = (struct bidi_it *) xrealloc (bidi_cache, BIDI_CACHE_CHUNK * elsz);
+ bidi_cache = xrealloc (bidi_cache, BIDI_CACHE_CHUNK * elsz);
bidi_cache_size = BIDI_CACHE_CHUNK;
}
bidi_cache_reset ();
}
-static inline void
+static void
bidi_cache_fetch_state (ptrdiff_t idx, struct bidi_it *bidi_it)
{
int current_scan_dir = bidi_it->scan_dir;
if (idx < bidi_cache_start || idx >= bidi_cache_idx)
- abort ();
+ emacs_abort ();
bidi_copy_it (bidi_it, &bidi_cache[idx]);
bidi_it->scan_dir = current_scan_dir;
level less or equal to LEVEL. if LEVEL is -1, disregard the
resolved levels in cached states. DIR, if non-zero, means search
in that direction from the last cache hit. */
-static inline ptrdiff_t
+static ptrdiff_t
bidi_cache_search (ptrdiff_t charpos, int level, int dir)
{
ptrdiff_t i, i_start;
that is lower than LEVEL, and return its cache slot index. DIR is
the direction to search, starting with the last used cache slot.
If DIR is zero, we search backwards from the last occupied cache
- slot. BEFORE, if non-zero, means return the index of the slot that
+ slot. BEFORE means return the index of the slot that
is ``before'' the level change in the search direction. That is,
given the cached levels like this:
and assuming we are at the position cached at the slot marked with
C, searching backwards (DIR = -1) for LEVEL = 2 will return the
index of slot B or A, depending whether BEFORE is, respectively,
- non-zero or zero. */
+ true or false. */
static ptrdiff_t
-bidi_cache_find_level_change (int level, int dir, int before)
+bidi_cache_find_level_change (int level, int dir, bool before)
{
if (bidi_cache_idx)
{
ptrdiff_t i = dir ? bidi_cache_last_idx : bidi_cache_idx - 1;
int incr = before ? 1 : 0;
- xassert (!dir || bidi_cache_last_idx >= 0);
+ eassert (!dir || bidi_cache_last_idx >= 0);
if (!dir)
dir = -1;
return -1;
}
-static inline void
+static void
bidi_cache_ensure_space (ptrdiff_t idx)
{
/* Enlarge the cache as needed. */
}
}
-static inline void
-bidi_cache_iterator_state (struct bidi_it *bidi_it, int resolved)
+static void
+bidi_cache_iterator_state (struct bidi_it *bidi_it, bool resolved)
{
ptrdiff_t idx;
/* We should never cache on backward scans. */
if (bidi_it->scan_dir == -1)
- abort ();
+ emacs_abort ();
idx = bidi_cache_search (bidi_it->charpos, -1, 1);
if (idx < 0)
idx = bidi_cache_start;
}
if (bidi_it->nchars <= 0)
- abort ();
+ emacs_abort ();
bidi_copy_it (&bidi_cache[idx], bidi_it);
if (!resolved)
bidi_cache[idx].resolved_level = -1;
bidi_cache_idx = idx + 1;
}
-static inline bidi_type_t
+static bidi_type_t
bidi_cache_find (ptrdiff_t charpos, int level, struct bidi_it *bidi_it)
{
ptrdiff_t i = bidi_cache_search (charpos, level, bidi_it->scan_dir);
return UNKNOWN_BT;
}
-static inline int
+static int
bidi_peek_at_next_level (struct bidi_it *bidi_it)
{
if (bidi_cache_idx == bidi_cache_start || bidi_cache_last_idx == -1)
- abort ();
+ emacs_abort ();
return bidi_cache[bidi_cache_last_idx + bidi_it->scan_dir].resolved_level;
}
/* Save the current iterator state in its entirety after the last
used cache slot. */
bidi_cache_ensure_space (bidi_cache_idx);
- memcpy (&bidi_cache[bidi_cache_idx++], bidi_it, sizeof (struct bidi_it));
+ bidi_cache[bidi_cache_idx++] = *bidi_it;
/* Push the current cache start onto the stack. */
- xassert (bidi_cache_sp < IT_STACK_SIZE);
+ eassert (bidi_cache_sp < IT_STACK_SIZE);
bidi_cache_start_stack[bidi_cache_sp++] = bidi_cache_start;
/* Start a new level of cache, and make it empty. */
bidi_pop_it (struct bidi_it *bidi_it)
{
if (bidi_cache_start <= 0)
- abort ();
+ emacs_abort ();
/* Reset the next free cache slot index to what it was before the
call to bidi_push_it. */
bidi_cache_idx = bidi_cache_start - 1;
/* Restore the bidi iterator state saved in the cache. */
- memcpy (bidi_it, &bidi_cache[bidi_cache_idx], sizeof (struct bidi_it));
+ *bidi_it = bidi_cache[bidi_cache_idx];
/* Pop the previous cache start from the stack. */
if (bidi_cache_sp <= 0)
- abort ();
+ emacs_abort ();
bidi_cache_start = bidi_cache_start_stack[--bidi_cache_sp];
/* Invalidate the last-used cache slot data. */
/* Restore the cache state from a copy stashed away by
bidi_shelve_cache, and free the buffer used to stash that copy.
- JUST_FREE non-zero means free the buffer, but don't restore the
+ JUST_FREE means free the buffer, but don't restore the
cache; used when the corresponding iterator is discarded instead of
being restored. */
void
-bidi_unshelve_cache (void *databuf, int just_free)
+bidi_unshelve_cache (void *databuf, bool just_free)
{
unsigned char *p = databuf;
{
bidi_type_table = uniprop_table (intern ("bidi-class"));
if (NILP (bidi_type_table))
- abort ();
+ emacs_abort ();
staticpro (&bidi_type_table);
bidi_mirror_table = uniprop_table (intern ("mirroring"));
if (NILP (bidi_mirror_table))
- abort ();
+ emacs_abort ();
staticpro (&bidi_mirror_table);
Qparagraph_start = intern ("paragraph-start");
/* Do whatever UAX#9 clause X8 says should be done at paragraph's
end. */
-static inline void
+static void
bidi_set_paragraph_end (struct bidi_it *bidi_it)
{
bidi_it->invalid_levels = 0;
/* Initialize the bidi iterator from buffer/string position CHARPOS. */
void
-bidi_init_it (ptrdiff_t charpos, ptrdiff_t bytepos, int frame_window_p,
+bidi_init_it (ptrdiff_t charpos, ptrdiff_t bytepos, bool frame_window_p,
struct bidi_it *bidi_it)
{
if (! bidi_initialized)
/* Count bytes in string S between BEG/BEGBYTE and END. BEG and END
are zero-based character positions in S, BEGBYTE is byte position
- corresponding to BEG. UNIBYTE, if non-zero, means S is a unibyte
- string. */
-static inline ptrdiff_t
-bidi_count_bytes (const unsigned char *s, const ptrdiff_t beg,
- const ptrdiff_t begbyte, const ptrdiff_t end, int unibyte)
+ corresponding to BEG. UNIBYTE means S is a unibyte string. */
+static ptrdiff_t
+bidi_count_bytes (const unsigned char *s, ptrdiff_t beg,
+ ptrdiff_t begbyte, ptrdiff_t end, bool unibyte)
{
ptrdiff_t pos = beg;
const unsigned char *p = s + begbyte, *start = p;
else
{
if (!CHAR_HEAD_P (*p))
- abort ();
+ emacs_abort ();
while (pos < end)
{
return p - start;
}
-/* Fetch and returns the character at byte position BYTEPOS. If S is
+/* Fetch and return the character at byte position BYTEPOS. If S is
non-NULL, fetch the character from string S; otherwise fetch the
- character from the current buffer. UNIBYTE non-zero means S is a
+ character from the current buffer. UNIBYTE means S is a
unibyte string. */
-static inline int
-bidi_char_at_pos (ptrdiff_t bytepos, const unsigned char *s, int unibyte)
+static int
+bidi_char_at_pos (ptrdiff_t bytepos, const unsigned char *s, bool unibyte)
{
if (s)
{
+ s += bytepos;
if (unibyte)
- return s[bytepos];
- else
- return STRING_CHAR (s + bytepos);
+ return *s;
}
else
- return FETCH_MULTIBYTE_CHAR (bytepos);
+ s = BYTE_POS_ADDR (bytepos);
+ return STRING_CHAR (s);
}
-/* Fetch and return the character at BYTEPOS/CHARPOS. If that
+/* Fetch and return the character at CHARPOS/BYTEPOS. If that
character is covered by a display string, treat the entire run of
covered characters as a single character, either u+2029 or u+FFFC,
and return their combined length in CH_LEN and NCHARS. DISP_POS
specifies the character position of the next display string, or -1
if not yet computed. When the next character is at or beyond that
position, the function updates DISP_POS with the position of the
- next display string. DISP_PROP non-zero means that there's really
+ next display string. *DISP_PROP non-zero means that there's really
a display string at DISP_POS, as opposed to when we searched till
- DISP_POS without finding one. If DISP_PROP is 2, it means the
+ DISP_POS without finding one. If *DISP_PROP is 2, it means the
display spec is of the form `(space ...)', which is replaced with
u+2029 to handle it as a paragraph separator. STRING->s is the C
string to iterate, or NULL if iterating over a buffer or a Lisp
string; in the latter case, STRING->lstring is the Lisp string. */
-static inline int
-bidi_fetch_char (ptrdiff_t bytepos, ptrdiff_t charpos, ptrdiff_t *disp_pos,
+static int
+bidi_fetch_char (ptrdiff_t charpos, ptrdiff_t bytepos, ptrdiff_t *disp_pos,
int *disp_prop, struct bidi_string_data *string,
- int frame_window_p, ptrdiff_t *ch_len, ptrdiff_t *nchars)
+ struct window *w,
+ bool frame_window_p, ptrdiff_t *ch_len, ptrdiff_t *nchars)
{
int ch;
ptrdiff_t endpos
if (charpos < endpos && charpos > *disp_pos)
{
SET_TEXT_POS (pos, charpos, bytepos);
- *disp_pos = compute_display_string_pos (&pos, string, frame_window_p,
+ *disp_pos = compute_display_string_pos (&pos, string, w, frame_window_p,
disp_prop);
}
/* We don't expect to find ourselves in the middle of a display
property. Hopefully, it will never be needed. */
if (charpos > *disp_pos)
- abort ();
+ emacs_abort ();
/* Text covered by `display' properties and overlays with
display properties or display strings is handled as a single
character that represents the entire run of characters
}
*nchars = disp_end_pos - *disp_pos;
if (*nchars <= 0)
- abort ();
+ emacs_abort ();
if (string->s)
*ch_len = bidi_count_bytes (string->s, *disp_pos, bytepos,
disp_end_pos, string->unibyte);
&& *disp_prop)
{
SET_TEXT_POS (pos, charpos + *nchars, bytepos + *ch_len);
- *disp_pos = compute_display_string_pos (&pos, string, frame_window_p,
+ *disp_pos = compute_display_string_pos (&pos, string, w, frame_window_p,
disp_prop);
}
return val;
}
+/* If the user has requested the long scans caching, make sure that
+ BIDI cache is enabled. Otherwise, make sure it's disabled. */
+
+static struct region_cache *
+bidi_paragraph_cache_on_off (void)
+{
+ struct buffer *cache_buffer = current_buffer;
+ bool indirect_p = false;
+
+ /* For indirect buffers, make sure to use the cache of their base
+ buffer. */
+ if (cache_buffer->base_buffer)
+ {
+ cache_buffer = cache_buffer->base_buffer;
+ indirect_p = true;
+ }
+
+ /* Don't turn on or off the cache in the base buffer, if the value
+ of cache-long-scans of the base buffer is inconsistent with that.
+ This is because doing so will just make the cache pure overhead,
+ since if we turn it on via indirect buffer, it will be
+ immediately turned off by its base buffer. */
+ if (NILP (BVAR (current_buffer, cache_long_scans)))
+ {
+ if (!indirect_p
+ || NILP (BVAR (cache_buffer, cache_long_scans)))
+ {
+ if (cache_buffer->bidi_paragraph_cache)
+ {
+ free_region_cache (cache_buffer->bidi_paragraph_cache);
+ cache_buffer->bidi_paragraph_cache = 0;
+ }
+ }
+ return NULL;
+ }
+ else
+ {
+ if (!indirect_p
+ || !NILP (BVAR (cache_buffer, cache_long_scans)))
+ {
+ if (!cache_buffer->bidi_paragraph_cache)
+ cache_buffer->bidi_paragraph_cache = new_region_cache ();
+ }
+ return cache_buffer->bidi_paragraph_cache;
+ }
+}
+
/* On my 2005-vintage machine, searching back for paragraph start
takes ~1 ms per line. And bidi_paragraph_init is called 4 times
when user types C-p. The number below limits each call to
{
Lisp_Object re = paragraph_start_re;
ptrdiff_t limit = ZV, limit_byte = ZV_BYTE;
- ptrdiff_t n = 0;
+ struct region_cache *bpc = bidi_paragraph_cache_on_off ();
+ ptrdiff_t n = 0, oldpos = pos, next;
+ struct buffer *cache_buffer = current_buffer;
+
+ if (cache_buffer->base_buffer)
+ cache_buffer = cache_buffer->base_buffer;
while (pos_byte > BEGV_BYTE
&& n++ < MAX_PARAGRAPH_SEARCH
display string? And what if a display string covering some
of the text over which we scan back includes
paragraph_start_re? */
- pos = find_next_newline_no_quit (pos - 1, -1);
- pos_byte = CHAR_TO_BYTE (pos);
+ DEC_BOTH (pos, pos_byte);
+ if (bpc && region_cache_backward (cache_buffer, bpc, pos, &next))
+ {
+ pos = next, pos_byte = CHAR_TO_BYTE (pos);
+ break;
+ }
+ else
+ pos = find_newline_no_quit (pos, pos_byte, -1, &pos_byte);
}
if (n >= MAX_PARAGRAPH_SEARCH)
- pos_byte = BEGV_BYTE;
+ pos = BEGV, pos_byte = BEGV_BYTE;
+ if (bpc)
+ know_region_cache (cache_buffer, bpc, pos, oldpos);
+ /* Positions returned by the region cache are not limited to
+ BEGV..ZV range, so we limit them here. */
+ pos_byte = clip_to_bounds (BEGV_BYTE, pos_byte, ZV_BYTE);
return pos_byte;
}
+/* On a 3.4 GHz machine, searching forward for a strong directional
+ character in a long paragraph full of weaks or neutrals takes about
+ 1 ms for each 20K characters. The number below limits each call to
+ bidi_paragraph_init to less than 10 ms even on slow machines. */
+#define MAX_STRONG_CHAR_SEARCH 100000
+
/* Determine the base direction, a.k.a. base embedding level, of the
paragraph we are about to iterate through. If DIR is either L2R or
R2L, just use that. Otherwise, determine the paragraph direction
from the first strong directional character of the paragraph.
- NO_DEFAULT_P non-zero means don't default to L2R if the paragraph
+ NO_DEFAULT_P means don't default to L2R if the paragraph
has no strong directional characters and both DIR and
bidi_it->paragraph_dir are NEUTRAL_DIR. In that case, search back
in the buffer until a paragraph is found with a strong character,
direction as the preceding paragraph, even though Emacs generally
views the separator as not belonging to any paragraph. */
void
-bidi_paragraph_init (bidi_dir_t dir, struct bidi_it *bidi_it, int no_default_p)
+bidi_paragraph_init (bidi_dir_t dir, struct bidi_it *bidi_it, bool no_default_p)
{
ptrdiff_t bytepos = bidi_it->bytepos;
- int string_p = bidi_it->string.s != NULL || STRINGP (bidi_it->string.lstring);
+ bool string_p = bidi_it->string.s || STRINGP (bidi_it->string.lstring);
ptrdiff_t pstartbyte;
/* Note that begbyte is a byte position, while end is a character
position. Yes, this is ugly, but we are trying to avoid costly
dir = L2R;
/* We should never be called at EOB or before BEGV. */
else if (bidi_it->charpos >= end || bytepos < begbyte)
- abort ();
+ emacs_abort ();
if (dir == L2R)
{
bidi_it->separator_limit = -1;
bidi_it->new_paragraph = 0;
- /* The following loop is run more than once only if NO_DEFAULT_P
- is non-zero, and only if we are iterating on a buffer. */
+ /* The following loop is run more than once only if NO_DEFAULT_P,
+ and only if we are iterating on a buffer. */
do {
+ ptrdiff_t pos1;
+
bytepos = pstartbyte;
if (!string_p)
pos = BYTE_TO_CHAR (bytepos);
- ch = bidi_fetch_char (bytepos, pos, &disp_pos, &disp_prop,
- &bidi_it->string,
+ ch = bidi_fetch_char (pos, bytepos, &disp_pos, &disp_prop,
+ &bidi_it->string, bidi_it->w,
bidi_it->frame_window_p, &ch_len, &nchars);
type = bidi_get_type (ch, NEUTRAL_DIR);
+ pos1 = pos;
for (pos += nchars, bytepos += ch_len;
- (bidi_get_category (type) != STRONG)
- || (bidi_ignore_explicit_marks_for_paragraph_level
- && (type == RLE || type == RLO
- || type == LRE || type == LRO));
+ ((bidi_get_category (type) != STRONG)
+ || (bidi_ignore_explicit_marks_for_paragraph_level
+ && (type == RLE || type == RLO
+ || type == LRE || type == LRO)))
+ /* Stop when searched too far into an abnormally large
+ paragraph full of weak or neutral characters. */
+ && pos - pos1 < MAX_STRONG_CHAR_SEARCH;
type = bidi_get_type (ch, NEUTRAL_DIR))
{
if (pos >= end)
&& bidi_at_paragraph_end (pos, bytepos) >= -1)
break;
/* Fetch next character and advance to get past it. */
- ch = bidi_fetch_char (bytepos, pos, &disp_pos,
- &disp_prop, &bidi_it->string,
+ ch = bidi_fetch_char (pos, bytepos, &disp_pos,
+ &disp_prop, &bidi_it->string, bidi_it->w,
bidi_it->frame_window_p, &ch_len, &nchars);
pos += nchars;
bytepos += ch_len;
/* FXIME: What if p is covered by a display
string? See also a FIXME inside
bidi_find_paragraph_start. */
- p--;
- pbyte = CHAR_TO_BYTE (p);
+ DEC_BOTH (p, pbyte);
prevpbyte = bidi_find_paragraph_start (p, pbyte);
}
pstartbyte = prevpbyte;
&& no_default_p && bidi_it->paragraph_dir == NEUTRAL_DIR);
}
else
- abort ();
+ emacs_abort ();
/* Contrary to UAX#9 clause P3, we only default the paragraph
direction to L2R if we have no previous usable paragraph
The rest of this file constitutes the core of the UBA implementation.
***********************************************************************/
-static inline int
+static bool
bidi_explicit_dir_char (int ch)
{
bidi_type_t ch_type;
if (!bidi_initialized)
- abort ();
+ emacs_abort ();
ch_type = (bidi_type_t) XINT (CHAR_TABLE_REF (bidi_type_table, ch));
return (ch_type == LRE || ch_type == LRO
|| ch_type == RLE || ch_type == RLO
int current_level;
int new_level;
bidi_dir_t override;
- int string_p = bidi_it->string.s != NULL || STRINGP (bidi_it->string.lstring);
+ bool string_p = bidi_it->string.s || STRINGP (bidi_it->string.lstring);
/* If reseat()'ed, don't advance, so as to start iteration from the
position where we were reseated. bidi_it->bytepos can be less
: bidi_it->string.s);
if (bidi_it->charpos < 0)
- bidi_it->charpos = 0;
- bidi_it->bytepos = bidi_count_bytes (p, 0, 0, bidi_it->charpos,
- bidi_it->string.unibyte);
+ bidi_it->charpos = bidi_it->bytepos = 0;
+ eassert (bidi_it->bytepos == bidi_count_bytes (p, 0, 0,
+ bidi_it->charpos,
+ bidi_it->string.unibyte));
}
else
{
if (bidi_it->charpos < BEGV)
- bidi_it->charpos = BEGV;
- bidi_it->bytepos = CHAR_TO_BYTE (bidi_it->charpos);
+ {
+ bidi_it->charpos = BEGV;
+ bidi_it->bytepos = BEGV_BYTE;
+ }
+ eassert (bidi_it->bytepos == CHAR_TO_BYTE (bidi_it->charpos));
}
}
/* Don't move at end of buffer/string. */
/* Advance to the next character, skipping characters covered by
display strings (nchars > 1). */
if (bidi_it->nchars <= 0)
- abort ();
+ emacs_abort ();
bidi_it->charpos += bidi_it->nchars;
if (bidi_it->ch_len == 0)
- abort ();
+ emacs_abort ();
bidi_it->bytepos += bidi_it->ch_len;
}
/* Fetch the character at BYTEPOS. If it is covered by a
display string, treat the entire run of covered characters as
a single character u+FFFC. */
- curchar = bidi_fetch_char (bidi_it->bytepos, bidi_it->charpos,
+ curchar = bidi_fetch_char (bidi_it->charpos, bidi_it->bytepos,
&bidi_it->disp_pos, &bidi_it->disp_prop,
- &bidi_it->string, bidi_it->frame_window_p,
+ &bidi_it->string, bidi_it->w,
+ bidi_it->frame_window_p,
&bidi_it->ch_len, &bidi_it->nchars);
}
bidi_it->ch = curchar;
}
if (bidi_it->nchars <= 0)
- abort ();
+ emacs_abort ();
if (level == prev_level) /* empty embedding */
saved_it.ignore_bn_limit = bidi_it->charpos + bidi_it->nchars;
else /* this embedding is non-empty */
|| type == RLE
|| type == RLO
|| type == PDF)
- abort ();
+ emacs_abort ();
if (new_level != prev_level
|| bidi_it->type == NEUTRAL_B)
else if (bidi_it->sor == L2R)
type = STRONG_L;
else /* shouldn't happen! */
- abort ();
+ emacs_abort ();
}
if (type == WEAK_EN /* W2 */
&& bidi_it->last_strong.type_after_w1 == STRONG_AL)
: bidi_it->string.s);
if (bidi_it->nchars <= 0)
- abort ();
+ emacs_abort ();
next_char
= (bidi_it->charpos + bidi_it->nchars >= eob
? BIDI_EOB
/* Resolve the type of a neutral character according to the type of
surrounding strong text and the current embedding level. */
-static inline bidi_type_t
+static bidi_type_t
bidi_resolve_neutral_1 (bidi_type_t prev_type, bidi_type_t next_type, int lev)
{
/* N1: European and Arabic numbers are treated as though they were R. */
|| type == NEUTRAL_S
|| type == NEUTRAL_WS
|| type == NEUTRAL_ON))
- abort ();
+ emacs_abort ();
if ((type != NEUTRAL_B /* Don't risk entering the long loop below if
we are already at paragraph end. */
bidi_type_t next_type;
if (bidi_it->scan_dir == -1)
- abort ();
+ emacs_abort ();
bidi_copy_it (&saved_it, bidi_it);
/* Scan the text forward until we find the first non-neutral
case STRONG_AL:
/* Actually, STRONG_AL cannot happen here, because
bidi_resolve_weak converts it to STRONG_R, per W3. */
- xassert (type != STRONG_AL);
+ eassert (type != STRONG_AL);
next_type = type;
break;
case WEAK_EN:
next_type = STRONG_R;
break;
case WEAK_BN:
+ case NEUTRAL_ON: /* W6/Retaining */
if (!bidi_explicit_dir_char (bidi_it->ch))
- abort (); /* can't happen: BNs are skipped */
+ emacs_abort (); /* can't happen: BNs are skipped */
/* FALLTHROUGH */
case NEUTRAL_B:
/* Marched all the way to the end of this level run.
}
break;
default:
- abort ();
+ emacs_abort ();
}
type = bidi_resolve_neutral_1 (saved_it.prev_for_neutral.type,
next_type, current_level);
/* This should always be called during a forward scan. */
if (bidi_it->scan_dir != 1)
- abort ();
+ emacs_abort ();
/* Reset the limit until which to ignore BNs if we step out of the
area where we found only empty levels. */
if (bidi_it->scan_dir > 0)
{
if (bidi_it->nchars <= 0)
- abort ();
+ emacs_abort ();
next_char_pos = bidi_it->charpos + bidi_it->nchars;
}
else if (bidi_it->charpos >= bob)
if (bidi_it->scan_dir == -1)
/* If we are going backwards, the iterator state is already cached
from previous scans, and should be fully resolved. */
- abort ();
+ emacs_abort ();
if (type == UNKNOWN_BT)
type = bidi_type_of_next_char (bidi_it);
|| (type == WEAK_BN && prev_level == level))
{
if (bidi_it->next_for_neutral.type == UNKNOWN_BT)
- abort ();
+ emacs_abort ();
/* If the cached state shows a neutral character, it was not
resolved by bidi_resolve_neutral, so do it now. */
|| type == WEAK_BN
|| type == WEAK_EN
|| type == WEAK_AN))
- abort ();
+ emacs_abort ();
bidi_it->type = type;
bidi_check_type (bidi_it->type);
ptrdiff_t nc = bidi_it->nchars;
struct bidi_string_data bs = bidi_it->string;
bidi_type_t chtype;
- int fwp = bidi_it->frame_window_p;
+ bool fwp = bidi_it->frame_window_p;
int dpp = bidi_it->disp_prop;
if (bidi_it->nchars <= 0)
- abort ();
+ emacs_abort ();
do {
- ch = bidi_fetch_char (bpos += clen, cpos += nc, &disp_pos, &dpp, &bs,
- fwp, &clen, &nc);
+ ch = bidi_fetch_char (cpos += nc, bpos += clen, &disp_pos, &dpp, &bs,
+ bidi_it->w, fwp, &clen, &nc);
if (ch == '\n' || ch == BIDI_EOB)
chtype = NEUTRAL_B;
else
return level;
}
-/* Move to the other edge of a level given by LEVEL. If END_FLAG is
- non-zero, we are at the end of a level, and we need to prepare to
+/* Move to the other edge of a level given by LEVEL. If END_FLAG,
+ we are at the end of a level, and we need to prepare to
resume the scan of the lower level.
If this level's other edge is cached, we simply jump to it, filling
function moves to point C, whereas the UAX#9 ``level 2 run'' ends
at point B. */
static void
-bidi_find_other_level_edge (struct bidi_it *bidi_it, int level, int end_flag)
+bidi_find_other_level_edge (struct bidi_it *bidi_it, int level, bool end_flag)
{
int dir = end_flag ? -bidi_it->scan_dir : bidi_it->scan_dir;
ptrdiff_t idx;
{
int new_level;
+ /* If we are at end of level, its edges must be cached. */
if (end_flag)
- abort (); /* if we are at end of level, its edges must be cached */
+ emacs_abort ();
bidi_cache_iterator_state (bidi_it, 1);
do {
struct gcpro gcpro1;
if (bidi_it->charpos < 0 || bidi_it->bytepos < 0)
- abort ();
+ emacs_abort ();
if (bidi_it->scan_dir == 0)
{
scanning the text whenever we find a level change. */
if (new_level != old_level)
{
- int ascending = new_level > old_level;
+ bool ascending = new_level > old_level;
int level_to_search = ascending ? old_level + 1 : old_level;
int incr = ascending ? 1 : -1;
int expected_next_level = old_level + incr;
next_level = bidi_peek_at_next_level (bidi_it);
while (next_level != expected_next_level)
{
+ /* If next_level is -1, it means we have an unresolved level
+ in the cache, which at this point should not happen. If
+ it does, we will infloop. */
+ eassert (next_level >= 0);
expected_next_level += incr;
level_to_search += incr;
bidi_find_other_level_edge (bidi_it, level_to_search, !ascending);
= bidi_at_paragraph_end (bidi_it->charpos + bidi_it->nchars,
bidi_it->bytepos + bidi_it->ch_len);
if (bidi_it->nchars <= 0)
- abort ();
+ emacs_abort ();
if (sep_len >= 0)
{
bidi_it->new_paragraph = 1;
HCoop / bpt / emacs.git / blobdiff