X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/56fd389cfb7656c00faa213c33ec52bb66c79bd2..32b158f23f2909163f0414b67706ae7b201cb7a2:/lib/unicode.c

diff --git a/lib/unicode.c b/lib/unicode.c
index 749916a..95c9f6d 100644
--- a/lib/unicode.c
+++ b/lib/unicode.c
@@ -21,7 +21,8 @@
  * @brief Unicode support functions
  *
  * Here by UTF-8 and UTF-8 we mean the encoding forms of those names (not the
- * encoding schemes).
+ * encoding schemes).  The primary encoding form is UTF-32 but convenience
+ * wrappers using UTF-8 are provided for a number of functions.
  *
  * The idea is that all the strings that hit the database will be in a
  * particular normalization form, and for the search and tags database
@@ -42,6 +43,115 @@
 #include "unicode.h"
 #include "unidata.h"
 
+/** @defgroup utf32props Unicode Code Point Properties */
+/*@{*/
+
+static const struct unidata *utf32__unidata_hard(uint32_t c);
+
+/** @brief Find definition of code point @p c
+ * @param c Code point
+ * @return Pointer to @ref unidata structure for @p c
+ *
+ * @p c can be any 32-bit value, a sensible value will be returned regardless.
+ * The returned pointer is NOT guaranteed to be unique to @p c.
+ */
+static inline const struct unidata *utf32__unidata(uint32_t c) {
+  /* The bottom half of the table contains almost everything of interest
+   * and we can just return the right thing straight away */
+  if(c < UNICODE_BREAK_START)
+    return &unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS];
+  else
+    return utf32__unidata_hard(c);
+}
+
+/** @brief Find definition of code point @p c
+ * @param c Code point
+ * @return Pointer to @ref unidata structure for @p c
+ *
+ * @p c can be any 32-bit value, a sensible value will be returned regardless.
+ * The returned pointer is NOT guaranteed to be unique to @p c.
+ *
+ * Don't use this function (although it will work fine) - use utf32__unidata()
+ * instead.
+ */
+static const struct unidata *utf32__unidata_hard(uint32_t c) {
+  if(c < UNICODE_BREAK_START)
+    return &unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS];
+  /* Within the break everything is unassigned */
+  if(c < UNICODE_BREAK_END)
+    return utf32__unidata(0xFFFF);      /* guaranteed to be Cn */
+  /* Planes 15 and 16 are (mostly) private use */
+  if((c >= 0xF0000 && c <= 0xFFFFD)
+     || (c >= 0x100000 && c <= 0x10FFFD))
+    return utf32__unidata(0xE000);      /* first Co code point */
+  /* Everything else above the break top is unassigned */
+  if(c >= UNICODE_BREAK_TOP)
+    return utf32__unidata(0xFFFF);      /* guaranteed to be Cn */
+  /* Currently the rest is language tags and variation selectors */
+  c -= (UNICODE_BREAK_END - UNICODE_BREAK_START);
+  return &unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS];
+}
+
+/** @brief Return the combining class of @p c
+ * @param c Code point
+ * @return Combining class of @p c
+ *
+ * @p c can be any 32-bit value, a sensible value will be returned regardless.
+ */
+static inline int utf32__combining_class(uint32_t c) {
+  return utf32__unidata(c)->ccc;
+}
+
+/** @brief Return the General_Category value for @p c
+ * @param Code point
+ * @return General_Category property value
+ *
+ * @p c can be any 32-bit value, a sensible value will be returned regardless.
+ */
+static inline enum unicode_General_Category utf32__general_category(uint32_t c) {
+  return utf32__unidata(c)->general_category;
+}
+
+/** @brief Determine Grapheme_Break property
+ * @param c Code point
+ * @return Grapheme_Break property value of @p c
+ *
+ * @p c can be any 32-bit value, a sensible value will be returned regardless.
+ */
+static inline enum unicode_Grapheme_Break utf32__grapheme_break(uint32_t c) {
+  return utf32__unidata(c)->grapheme_break;
+}
+
+/** @brief Determine Word_Break property
+ * @param c Code point
+ * @return Word_Break property value of @p c
+ *
+ * @p c can be any 32-bit value, a sensible value will be returned regardless.
+ */
+static inline enum unicode_Word_Break utf32__word_break(uint32_t c) {
+  return utf32__unidata(c)->word_break;
+}
+
+/** @brief Determine Sentence_Break property
+ * @param c Code point
+ * @return Word_Break property value of @p c
+ *
+ * @p c can be any 32-bit value, a sensible value will be returned regardless.
+ */
+static inline enum unicode_Sentence_Break utf32__sentence_break(uint32_t c) {
+  return utf32__unidata(c)->sentence_break;
+}
+
+/** @brief Return true if @p c is ignorable for boundary specifications
+ * @param wb Word break property value
+ * @return non-0 if @p wb is unicode_Word_Break_Extend or unicode_Word_Break_Format
+ */
+static inline int utf32__boundary_ignorable(enum unicode_Word_Break wb) {
+  return (wb == unicode_Word_Break_Extend
+          || wb == unicode_Word_Break_Format);
+}
+
+/*@}*/
 /** @defgroup utftransform Functions that transform between different Unicode encoding forms */
 /*@{*/
 
@@ -112,69 +222,46 @@ error:
  */
 uint32_t *utf8_to_utf32(const char *s, size_t ns, size_t *ndp) {
   struct dynstr_ucs4 d;
-  uint32_t c32, c;
+  uint32_t c32;
   const uint8_t *ss = (const uint8_t *)s;
+  int n;
 
   dynstr_ucs4_init(&d);
   while(ns > 0) {
-    c = *ss++;
-    --ns;
-    /* Acceptable UTF-8 is that which codes for Unicode Scalar Values
-     * (Unicode 5.0.0 s3.9 D76)
-     *
-     * 0xxxxxxx
-     * 7 data bits gives 0x00 - 0x7F and all are acceptable
-     * 
-     * 110xxxxx 10xxxxxx
-     * 11 data bits gives 0x0000 - 0x07FF but only 0x0080 - 0x07FF acceptable
-     *   
-     * 1110xxxx 10xxxxxx 10xxxxxx
-     * 16 data bits gives 0x0000 - 0xFFFF but only 0x0800 - 0xFFFF acceptable
-     * (and UTF-16 surrogates are not acceptable)
-     *
-     * 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
-     * 21 data bits gives 0x00000000 - 0x001FFFFF
-     * but only           0x00010000 - 0x0010FFFF are acceptable
-     *
-     * It is NOT always the case that the data bits in the first byte are
-     * always non-0 for the acceptable values, so we do a separate check after
-     * decoding.
-     */
-    if(c < 0x80)
-      c32 = c;
-    else if(c <= 0xDF) {
-      if(ns < 1) goto error;
-      c32 = c & 0x1F;
-      c = *ss++;
-      if((c & 0xC0) != 0x80) goto error;
-      c32 = (c32 << 6) | (c & 0x3F);
-      if(c32 < 0x80) goto error;
-    } else if(c <= 0xEF) {
-      if(ns < 2) goto error;
-      c32 = c & 0x0F;
-      c = *ss++;
-      if((c & 0xC0) != 0x80) goto error;
-      c32 = (c32 << 6) | (c & 0x3F);
-      c = *ss++;
-      if((c & 0xC0) != 0x80) goto error;
-      c32 = (c32 << 6) | (c & 0x3F);
-      if(c32 < 0x0800 || (c32 >= 0xD800 && c32 <= 0xDFFF)) goto error;
-    } else if(c <= 0xF7) {
-      if(ns < 3) goto error;
-      c32 = c & 0x07;
-      c = *ss++;
-      if((c & 0xC0) != 0x80) goto error;
-      c32 = (c32 << 6) | (c & 0x3F);
-      c = *ss++;
-      if((c & 0xC0) != 0x80) goto error;
-      c32 = (c32 << 6) | (c & 0x3F);
-      c = *ss++;
-      if((c & 0xC0) != 0x80) goto error;
-      c32 = (c32 << 6) | (c & 0x3F);
-      if(c32 < 0x00010000 || c32 > 0x0010FFFF) goto error;
+    const struct unicode_utf8_row *const r = &unicode_utf8_valid[*ss];
+    if(r->count <= ns) {
+      switch(r->count) {
+      case 1:
+        c32 = *ss;
+        break;
+      case 2:
+        if(ss[1] < r->min2 || ss[1] > r->max2)
+          goto error;
+        c32 = *ss & 0x1F;
+        break;
+      case 3:
+        if(ss[1] < r->min2 || ss[1] > r->max2)
+          goto error;
+        c32 = *ss & 0x0F;
+        break;
+      case 4:
+        if(ss[1] < r->min2 || ss[1] > r->max2)
+          goto error;
+        c32 = *ss & 0x07;
+        break;
+      default:
+        goto error;
+      }
     } else
       goto error;
+    for(n = 1; n < r->count; ++n) {
+      if(ss[n] < 0x80 || ss[n] > 0xBF)
+        goto error;
+      c32 = (c32 << 6) | (ss[n] & 0x3F);
+    }
     dynstr_ucs4_append(&d, c32);
+    ss += r->count;
+    ns -= r->count;
   }
   dynstr_ucs4_terminate(&d);
   if(ndp)
@@ -185,6 +272,342 @@ error:
   return 0;
 }
 
+/** @brief Test whether [s,s+ns) is valid UTF-8
+ * @param s Start of string
+ * @param ns Length of string
+ * @return non-0 if @p s is valid UTF-8, 0 if it is not valid
+ *
+ * This function is intended to be much faster than calling utf8_to_utf32() and
+ * throwing away the result.
+ */
+int utf8_valid(const char *s, size_t ns) {
+  const uint8_t *ss = (const uint8_t *)s;
+  while(ns > 0) {
+    const struct unicode_utf8_row *const r = &unicode_utf8_valid[*ss];
+    if(r->count <= ns) {
+      switch(r->count) {
+      case 1:
+        break;
+      case 2:
+        if(ss[1] < r->min2 || ss[1] > r->max2)
+          return 0;
+        break;
+      case 3:
+        if(ss[1] < r->min2 || ss[1] > r->max2)
+          return 0;
+        if(ss[2] < 0x80 || ss[2] > 0xBF)
+          return 0;
+        break;
+      case 4:
+        if(ss[1] < r->min2 || ss[1] > r->max2)
+          return 0;
+        if(ss[2] < 0x80 || ss[2] > 0xBF)
+          return 0;
+        if(ss[3] < 0x80 || ss[3] > 0xBF)
+          return 0;
+        break;
+      default:
+        return 0;
+      }
+    } else
+      return 0;
+    ss += r->count;
+    ns -= r->count;
+  }
+  return 1;
+}
+
+/*@}*/
+/** @defgroup utf32iterator UTF-32 string iterators */
+/*@{*/
+
+struct utf32_iterator_data {
+  /** @brief Start of string */
+  const uint32_t *s;
+
+  /** @brief Length of string */
+  size_t ns;
+
+  /** @brief Current position */
+  size_t n;
+
+  /** @brief Last two non-ignorable characters or (uint32_t)-1
+   *
+   * last[1] is the non-Extend/Format character just before position @p n;
+   * last[0] is the one just before that.
+   *
+   * Exception 1: if there is no such non-Extend/Format character then an
+   * Extend/Format character is accepted instead.
+   *
+   * Exception 2: if there is no such character even taking that into account
+   * the value is (uint32_t)-1.
+   */
+  uint32_t last[2];
+};
+
+/** @brief Create a new iterator pointing at the start of a string
+ * @param s Start of string
+ * @param ns Length of string
+ * @return New iterator
+ */
+utf32_iterator utf32_iterator_new(const uint32_t *s, size_t ns) {
+  utf32_iterator it = xmalloc(sizeof *it);
+  it->s = s;
+  it->ns = ns;
+  it->n = 0;
+  it->last[0] = it->last[1] = -1;
+  return it;
+}
+
+/** @brief Initialize an internal private iterator
+ * @param it Iterator
+ * @param s Start of string
+ * @param ns Length of string
+ * @param n Absolute position
+ */
+static void utf32__iterator_init(utf32_iterator it,
+                                 const uint32_t *s, size_t ns, size_t n) {
+  it->s = s;
+  it->ns = ns;
+  it->n = 0;
+  it->last[0] = it->last[1] = -1;
+  utf32_iterator_advance(it, n);
+}
+
+/** @brief Destroy an iterator
+ * @param it Iterator
+ */
+void utf32_iterator_destroy(utf32_iterator it) {
+  xfree(it);
+}
+
+/** @brief Find the current position of an interator
+ * @param it Iterator
+ */
+size_t utf32_iterator_where(utf32_iterator it) {
+  return it->n;
+}
+
+/** @brief Set an iterator's absolute position
+ * @param it Iterator
+ * @param n Absolute position
+ * @return 0 on success, non-0 on error
+ *
+ * It is an error to position the iterator outside the string (but acceptable
+ * to point it at the hypothetical post-final character).  If an invalid value
+ * of @p n is specified then the iterator is not changed.
+ */
+int utf32_iterator_set(utf32_iterator it, size_t n) {
+  /* TODO figure out how far we must back up to be able to re-synchronize; see
+   * UAX #29 s6.4. */
+  if(n > it->ns)
+    return -1;
+  if(n >= it->n)
+    n -= it->n;
+  else {
+    it->n = 0;
+    it->last[0] = it->last[1] = -1;
+  }
+  return utf32_iterator_advance(it, n);
+}
+
+/** @brief Advance an iterator
+ * @param it Iterator
+ * @param count Number of code points to advance by
+ * @return 0 on success, non-0 on error
+ *
+ * It is an error to advance an iterator beyond the hypothetical post-final
+ * character of the string.  If an invalid value of @p n is specified then the
+ * iterator is not changed.
+ *
+ * This function has O(n) time complexity: it works by advancing naively
+ * forwards through the string.
+ */
+int utf32_iterator_advance(utf32_iterator it, size_t count) {
+  if(count <= it->ns - it->n) {
+    while(count > 0) {
+      const uint32_t c = it->s[it->n];
+      const enum unicode_Word_Break wb = utf32__word_break(c);
+      if(it->last[1] == (uint32_t)-1
+         || !utf32__boundary_ignorable(wb)) {
+        it->last[0] = it->last[1];
+        it->last[1] = c;
+      }
+      ++it->n;
+      --count;
+    }
+    return 0;
+  } else
+    return -1;
+}
+
+/** @brief Find the current code point
+ * @param it Iterator
+ * @return Current code point or 0
+ *
+ * If the iterator points at the hypothetical post-final character of the
+ * string then 0 is returned.  NB that this doesn't mean that there aren't any
+ * 0 code points inside the string!
+ */
+uint32_t utf32_iterator_code(utf32_iterator it) {
+  if(it->n < it->ns)
+    return it->s[it->n];
+  else
+    return 0;
+}
+
+/** @brief Test for a grapheme boundary
+ * @param it Iterator
+ * @return Non-0 if pointing just after a grapheme boundary, otherwise 0
+ */
+int utf32_iterator_grapheme_boundary(utf32_iterator it) {
+  uint32_t before, after;
+  enum unicode_Grapheme_Break gbbefore, gbafter;
+  /* GB1 and GB2 */
+  if(it->n == 0 || it->n == it->ns)
+    return 1;
+  /* Now we know that s[n-1] and s[n] are safe to inspect */
+  /* GB3 */
+  before = it->s[it->n-1];
+  after = it->s[it->n];
+  if(before == 0x000D && after == 0x000A)
+    return 0;
+  gbbefore = utf32__grapheme_break(before);
+  gbafter = utf32__grapheme_break(after);
+  /* GB4 */
+  if(gbbefore == unicode_Grapheme_Break_Control
+     || before == 0x000D
+     || before == 0x000A)
+    return 1;
+  /* GB5 */
+  if(gbafter == unicode_Grapheme_Break_Control
+     || after == 0x000D
+     || after == 0x000A)
+    return 1;
+  /* GB6 */
+  if(gbbefore == unicode_Grapheme_Break_L
+     && (gbafter == unicode_Grapheme_Break_L
+         || gbafter == unicode_Grapheme_Break_V
+         || gbafter == unicode_Grapheme_Break_LV
+         || gbafter == unicode_Grapheme_Break_LVT))
+    return 0;
+  /* GB7 */
+  if((gbbefore == unicode_Grapheme_Break_LV
+      || gbbefore == unicode_Grapheme_Break_V)
+     && (gbafter == unicode_Grapheme_Break_V
+         || gbafter == unicode_Grapheme_Break_T))
+    return 0;
+  /* GB8 */
+  if((gbbefore == unicode_Grapheme_Break_LVT
+      || gbbefore == unicode_Grapheme_Break_T)
+     && gbafter == unicode_Grapheme_Break_T)
+    return 0;
+  /* GB9 */
+  if(gbafter == unicode_Grapheme_Break_Extend)
+    return 0;
+  /* GB10 */
+  return 1;
+
+}
+
+/** @brief Test for a word boundary
+ * @param it Iterator
+ * @return Non-0 if pointing just after a word boundary, otherwise 0
+ */
+int utf32_iterator_word_boundary(utf32_iterator it) {
+  enum unicode_Word_Break twobefore, before, after, twoafter;
+  size_t nn;
+
+  /* WB1 and WB2 */
+  if(it->n == 0 || it->n == it->ns)
+    return 1;
+  /* WB3 */
+  if(it->s[it->n-1] == 0x000D && it->s[it->n] == 0x000A)
+    return 0;
+  /* WB4 */
+  /* (!Sep) x (Extend|Format) as in UAX #29 s6.2 */
+  if(utf32__sentence_break(it->s[it->n-1]) != unicode_Sentence_Break_Sep
+     && utf32__boundary_ignorable(utf32__word_break(it->s[it->n])))
+    return 0;
+  /* Gather the property values we'll need for the rest of the test taking the
+   * s6.2 changes into account */
+  /* First we look at the code points after the proposed boundary */
+  nn = it->n;                           /* <it->ns */
+  after = utf32__word_break(it->s[nn++]);
+  if(!utf32__boundary_ignorable(after)) {
+    /* X (Extend|Format)* -> X */
+    while(nn < it->ns
+          && utf32__boundary_ignorable(utf32__word_break(it->s[nn])))
+      ++nn;
+  }
+  /* It's possible now that nn=ns */
+  if(nn < it->ns)
+    twoafter = utf32__word_break(it->s[nn]);
+  else
+    twoafter = unicode_Word_Break_Other;
+
+  /* We've already recorded the non-ignorable code points before the proposed
+   * boundary */
+  before = utf32__word_break(it->last[1]);
+  twobefore = utf32__word_break(it->last[0]);
+
+  /* WB5 */
+  if(before == unicode_Word_Break_ALetter
+     && after == unicode_Word_Break_ALetter)
+    return 0;
+  /* WB6 */
+  if(before == unicode_Word_Break_ALetter
+     && after == unicode_Word_Break_MidLetter
+     && twoafter == unicode_Word_Break_ALetter)
+    return 0;
+  /* WB7 */
+  if(twobefore == unicode_Word_Break_ALetter
+     && before == unicode_Word_Break_MidLetter
+     && after == unicode_Word_Break_ALetter)
+    return 0;
+  /* WB8 */  
+  if(before == unicode_Word_Break_Numeric
+     && after == unicode_Word_Break_Numeric)
+    return 0;
+  /* WB9 */
+  if(before == unicode_Word_Break_ALetter
+     && after == unicode_Word_Break_Numeric)
+    return 0;
+  /* WB10 */
+  if(before == unicode_Word_Break_Numeric
+     && after == unicode_Word_Break_ALetter)
+    return 0;
+   /* WB11 */
+  if(twobefore == unicode_Word_Break_Numeric
+     && before == unicode_Word_Break_MidNum
+     && after == unicode_Word_Break_Numeric)
+    return 0;
+  /* WB12 */
+  if(before == unicode_Word_Break_Numeric
+     && after == unicode_Word_Break_MidNum
+     && twoafter == unicode_Word_Break_Numeric)
+    return 0;
+  /* WB13 */
+  if(before == unicode_Word_Break_Katakana
+     && after == unicode_Word_Break_Katakana)
+    return 0;
+  /* WB13a */
+  if((before == unicode_Word_Break_ALetter
+      || before == unicode_Word_Break_Numeric
+      || before == unicode_Word_Break_Katakana
+      || before == unicode_Word_Break_ExtendNumLet)
+     && after == unicode_Word_Break_ExtendNumLet)
+    return 0;
+  /* WB13b */
+  if(before == unicode_Word_Break_ExtendNumLet
+     && (after == unicode_Word_Break_ALetter
+         || after == unicode_Word_Break_Numeric
+         || after == unicode_Word_Break_Katakana))
+    return 0;
+  /* WB14 */
+  return 1;
+}
+
 /*@}*/
 /** @defgroup utf32 Functions that operate on UTF-32 strings */
 /*@{*/
@@ -203,16 +626,6 @@ size_t utf32_len(const uint32_t *s) {
   return (size_t)(t - s);
 }
 
-/** @brief Return the combining class of @p c
- * @param c Code point
- * @return Combining class of @p c
- */
-static inline int utf32__combining_class(uint32_t c) {
-  if(c < UNICODE_NCHARS)
-    return unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS].ccc;
-  return 0;
-}
-
 /** @brief Stably sort [s,s+ns) into descending order of combining class
  * @param s Start of array
  * @param ns Number of elements, must be at least 1
@@ -319,10 +732,7 @@ static int utf32__canonical_ordering(uint32_t *s, size_t ns) {
 
 /** @brief Guts of the decomposition lookup functions */
 #define utf32__decompose_one_generic(WHICH) do {                        \
-  const uint32_t *dc =                                                  \
-    (c < UNICODE_NCHARS                                                 \
-     ? unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS].WHICH          \
-     : 0);                                                              \
+  const uint32_t *dc = utf32__unidata(c)->WHICH;                        \
   if(dc) {                                                              \
     /* Found a canonical decomposition in the table */                  \
     while(*dc)                                                          \
@@ -424,10 +834,7 @@ uint32_t *utf32_decompose_compat(const uint32_t *s, size_t ns, size_t *ndp) {
 
 /** @brief Single-character case-fold and decompose operation */
 #define utf32__casefold_one(WHICH) do {                                 \
-  const uint32_t *cf =                                                  \
-     (c < UNICODE_NCHARS                                                \
-      ? unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS].casefold      \
-      : 0);                                                             \
+  const uint32_t *cf = utf32__unidata(c)->casefold;                     \
   if(cf) {                                                              \
     /* Found a case-fold mapping in the table */                        \
     while(*cf)                                                          \
@@ -460,13 +867,9 @@ uint32_t *utf32_casefold_canon(const uint32_t *s, size_t ns, size_t *ndp) {
    * normalize before we fold.  In Unicode 5.0.0 this means 0345 COMBINING
    * GREEK YPOGEGRAMMENI in its decomposition and the various characters that
    * canonically decompose to it. */
-  for(n = 0; n < ns; ++n) {
-    c = s[n];
-    if(c < UNICODE_NCHARS
-       && (unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS].flags
-           & unicode_normalize_before_casefold))
+  for(n = 0; n < ns; ++n)
+    if(utf32__unidata(s[n])->flags & unicode_normalize_before_casefold)
       break;
-  }
   if(n < ns) {
     /* We need a preliminary decomposition */
     if(!(ss = utf32_decompose_canon(s, ns, &ns)))
@@ -512,13 +915,9 @@ uint32_t *utf32_casefold_compat(const uint32_t *s, size_t ns, size_t *ndp) {
   size_t n;
   uint32_t *ss = 0;
 
-  for(n = 0; n < ns; ++n) {
-    c = s[n];
-    if(c < UNICODE_NCHARS
-       && (unidata[c / UNICODE_MODULUS][c % UNICODE_MODULUS].flags
-           & unicode_normalize_before_casefold))
+  for(n = 0; n < ns; ++n)
+    if(utf32__unidata(s[n])->flags & unicode_normalize_before_casefold)
       break;
-  }
   if(n < ns) {
     /* We need a preliminary _canonical_ decomposition */
     if(!(ss = utf32_decompose_canon(s, ns, &ns)))
@@ -572,8 +971,43 @@ int utf32_cmp(const uint32_t *a, const uint32_t *b) {
   return *a < *b ? -1 : (*a > *b ? 1 : 0);
 }
 
+/** @brief Identify a grapheme cluster boundary
+ * @param s Start of string (must be NFD)
+ * @param ns Length of string
+ * @param n Index within string (in [0,ns].)
+ * @return 1 at a grapheme cluster boundary, 0 otherwise
+ *
+ * This function identifies default grapheme cluster boundaries as described in
+ * UAX #29 s3.  It returns 1 if @p n points at the code point just after a
+ * grapheme cluster boundary (including the hypothetical code point just after
+ * the end of the string).
+ */
+int utf32_is_grapheme_boundary(const uint32_t *s, size_t ns, size_t n) {
+  struct utf32_iterator_data it[1];
+
+  utf32__iterator_init(it, s, ns, n);
+  return utf32_iterator_grapheme_boundary(it);
+}
+
+/** @brief Identify a word boundary
+ * @param s Start of string (must be NFD)
+ * @param ns Length of string
+ * @param n Index within string (in [0,ns].)
+ * @return 1 at a word boundary, 0 otherwise
+ *
+ * This function identifies default word boundaries as described in UAX #29 s4.
+ * It returns 1 if @p n points at the code point just after a word boundary
+ * (including the hypothetical code point just after the end of the string).
+ */
+int utf32_is_word_boundary(const uint32_t *s, size_t ns, size_t n) {
+  struct utf32_iterator_data it[1];
+
+  utf32__iterator_init(it, s, ns, n);
+  return utf32_iterator_word_boundary(it);
+}
+
 /*@}*/
-/** @defgroup Functions that operate on UTF-8 strings */
+/** @defgroup utf8 Functions that operate on UTF-8 strings */
 /*@{*/
 
 /** @brief Wrapper to transform a UTF-8 string using the UTF-32 function */