16-bit update of non-man documentation files and the PrepareRelease script.

git-svn-id: svn://vcs.exim.org/pcre/code/trunk@840 2f5784b3-3f2a-0410-8824-cb99058d5e15

1 files changed, 90 insertions, 73 deletions

diff --git a/HACKING b/HACKING
index bc92560..2fa365c 100644
--- a/HACKING
+++ b/HACKING
@@ -49,6 +49,18 @@ complexity in Perl regular expressions, I couldn't do this. In any case, a
 first pass through the pattern is helpful for other reasons. 
 
 
+Support for 16-bit data strings
+-------------------------------
+
+From release 8.30, PCRE supports 16-bit as well as 8-bit data strings, by being 
+compilable in either 8-bit or 16-bit modes, or both. Thus, two different 
+libraries can be created. In the description that follows, the word "short" is 
+used for a 16-bit data quantity, and the word "unit" is used for a quantity
+that is a byte in 8-bit mode and a short in 16-bit mode. However, so as not to
+over-complicate the text, the names of PCRE functions are given in 8-bit form
+only.
+
+
 Computing the memory requirement: how it was
 --------------------------------------------
 
@@ -125,23 +137,25 @@ any more.
 Format of compiled patterns
 ---------------------------
 
-The compiled form of a pattern is a vector of bytes, containing items of
-variable length. The first byte in an item is an opcode, and the length of the
-item is either implicit in the opcode or contained in the data bytes that
-follow it. 
-
-In many cases below LINK_SIZE data values are specified for offsets within the 
-compiled pattern. The default value for LINK_SIZE is 2, but PCRE can be
-compiled to use 3-byte or 4-byte values for these offsets (impairing the
-performance). This is necessary only when patterns whose compiled length is
-greater than 64K are going to be processed. In this description, we assume the
-"normal" compilation options. Data values that are counts (e.g. for
-quantifiers) are always just two bytes long.
+The compiled form of a pattern is a vector of units (bytes in 8-bit mode, or
+shorts in 16-bit mode), containing items of variable length. The first unit in
+an item contains an opcode, and the length of the item is either implicit in
+the opcode or contained in the data that follows it.
+
+In many cases listed below, LINK_SIZE data values are specified for offsets
+within the compiled pattern. LINK_SIZE always specifies a number of bytes. The
+default value for LINK_SIZE is 2, but PCRE can be compiled to use 3-byte or
+4-byte values for these offsets, although this impairs the performance. (3-byte
+LINK_SIZE values are available only in 8-bit mode.) Specifing a LINK_SIZE
+larger than 2 is necessary only when patterns whose compiled length is greater
+than 64K are going to be processed. In this description, we assume the "normal"
+compilation options. Data values that are counts (e.g. for quantifiers) are
+always just two bytes long (one short in 16-bit mode).
 
 Opcodes with no following data
 ------------------------------
 
-These items are all just one byte long
+These items are all just one unit long
 
   OP_END                 end of pattern
   OP_ANY                 match any one character other than newline
@@ -182,7 +196,7 @@ Backtracking control verbs with (optional) data
 -----------------------------------------------
 
 (*THEN) without an argument generates the opcode OP_THEN and no following data.
-OP_MARK is followed by the mark name, preceded by a one-byte length, and
+OP_MARK is followed by the mark name, preceded by a one-unit length, and
 followed by a binary zero. For (*PRUNE), (*SKIP), and (*THEN) with arguments,
 the opcodes OP_PRUNE_ARG, OP_SKIP_ARG, and OP_THEN_ARG are used, with the name
 following in the same format.
@@ -192,16 +206,14 @@ Matching literal characters
 ---------------------------
 
 The OP_CHAR opcode is followed by a single character that is to be matched 
-casefully. For caseless matching, OP_CHARI is used. In UTF-8 mode, the 
-character may be more than one byte long. (Earlier versions of PCRE used 
-multi-character strings, but this was changed to allow some new features to be 
-added.)
+casefully. For caseless matching, OP_CHARI is used. In UTF-8 or UTF-16 modes,
+the character may be more than one unit long.
 
 
 Repeating single characters
 ---------------------------
 
-The common repeats (*, +, ?) when applied to a single character use the
+The common repeats (*, +, ?), when applied to a single character, use the
 following opcodes, which come in caseful and caseless versions:
 
   Caseful         Caseless
@@ -215,10 +227,11 @@ following opcodes, which come in caseful and caseless versions:
   OP_MINQUERY     OP_MINQUERYI  
   OP_POSQUERY     OP_POSQUERYI  
 
-In ASCII mode, these are two-byte items; in UTF-8 mode, the length is variable.
-Those with "MIN" in their name are the minimizing versions. Those with "POS" in 
-their names are possessive versions. Each is followed by the character that is
-to be repeated. Other repeats make use of these opcodes:
+Each opcode is followed by the character that is to be repeated. In ASCII mode,
+these are two-unit items; in UTF-8 or UTF-16 modes, the length is variable.
+Those with "MIN" in their names are the minimizing versions. Those with "POS"
+in their names are possessive versions. Other repeats make use of these
+opcodes:
 
   Caseful         Caseless
   OP_UPTO         OP_UPTOI    
@@ -226,10 +239,10 @@ to be repeated. Other repeats make use of these opcodes:
   OP_POSUPTO      OP_POSUPTOI 
   OP_EXACT        OP_EXACTI   
 
-Each of these is followed by a two-byte count (most significant first) and the
-repeated character. OP_UPTO matches from 0 to the given number. A repeat with a
-non-zero minimum and a fixed maximum is coded as an OP_EXACT followed by an
-OP_UPTO (or OP_MINUPTO or OPT_POSUPTO).
+Each of these is followed by a two-byte (one short) count (most significant
+byte first in 8-bit mode) and then the repeated character. OP_UPTO matches from
+0 to the given number. A repeat with a non-zero minimum and a fixed maximum is
+coded as an OP_EXACT followed by an OP_UPTO (or OP_MINUPTO or OPT_POSUPTO).
 
 
 Repeating character types
@@ -237,7 +250,7 @@ Repeating character types
 
 Repeats of things like \d are done exactly as for single characters, except
 that instead of a character, the opcode for the type is stored in the data
-byte. The opcodes are:
+unit. The opcodes are:
 
   OP_TYPESTAR
   OP_TYPEMINSTAR
@@ -259,49 +272,51 @@ Match by Unicode property
 
 OP_PROP and OP_NOTPROP are used for positive and negative matches of a 
 character by testing its Unicode property (the \p and \P escape sequences).
-Each is followed by two bytes that encode the desired property as a type and a 
+Each is followed by two units that encode the desired property as a type and a
 value.
 
-Repeats of these items use the OP_TYPESTAR etc. set of opcodes, followed by 
-three bytes: OP_PROP or OP_NOTPROP and then the desired property type and 
+Repeats of these items use the OP_TYPESTAR etc. set of opcodes, followed by
+three units: OP_PROP or OP_NOTPROP, and then the desired property type and
 value.
 
 
 Character classes
 -----------------
 
-If there is only one character, OP_CHAR or OP_CHARI is used for a positive
-class, and OP_NOT or OP_NOTI for a negative one (that is, for something like
-[^a]). However, in UTF-8 mode, the use of OP_NOT[I] applies only to characters
-with values < 128, because OP_NOT[I] is confined to single bytes.
+If there is only one character in the class, OP_CHAR or OP_CHARI is used for a
+positive class, and OP_NOT or OP_NOTI for a negative one (that is, for
+something like [^a]). However, OP_NOT[I] can be used only with single-unit
+characters, so in UTF-8 (UTF-16) mode, the use of OP_NOT[I] applies only to
+characters whose code points are no greater than 127 (0xffff).
 
-Another set of 13 repeating opcodes (called OP_NOTSTAR etc.) are used for a
-repeated, negated, single-character class. The normal single-character opcodes
-(OP_STAR, etc.) are used for a repeated positive single-character class.
+Another set of 13 repeating opcodes (called OP_NOTSTAR etc.) are used for
+repeated, negated, single-character classes. The normal single-character
+opcodes (OP_STAR, etc.) are used for repeated positive single-character
+classes.
 
 When there is more than one character in a class and all the characters are
 less than 256, OP_CLASS is used for a positive class, and OP_NCLASS for a
-negative one. In either case, the opcode is followed by a 32-byte bit map
-containing a 1 bit for every character that is acceptable. The bits are counted
-from the least significant end of each byte. In caseless mode, bits for both 
-cases are set.
+negative one. In either case, the opcode is followed by a 32-byte (16-short)
+bit map containing a 1 bit for every character that is acceptable. The bits are
+counted from the least significant end of each unit. In caseless mode, bits for
+both cases are set.
 
-The reason for having both OP_CLASS and OP_NCLASS is so that, in UTF-8 mode,
-subject characters with values greater than 256 can be handled correctly. For
+The reason for having both OP_CLASS and OP_NCLASS is so that, in UTF-8/16 mode,
+subject characters with values greater than 255 can be handled correctly. For
 OP_CLASS they do not match, whereas for OP_NCLASS they do.
 
-For classes containing characters with values > 255, OP_XCLASS is used. It
-optionally uses a bit map (if any characters lie within it), followed by a list
-of pairs (for a range) and single characters. In caseless mode, both cases are 
-explicitly listed. There is a flag character than indicates whether it is a
-positive or a negative class.
+For classes containing characters with values greater than 255, OP_XCLASS is
+used. It optionally uses a bit map (if any characters lie within it), followed
+by a list of pairs (for a range) and single characters. In caseless mode, both
+cases are explicitly listed. There is a flag character than indicates whether
+it is a positive or a negative class.
 
 
 Back references
 ---------------
 
-OP_REF (caseful) or OP_REFI (caseless) is followed by two bytes containing the
-reference number.
+OP_REF (caseful) or OP_REFI (caseless) is followed by two bytes (one short)
+containing the reference number.
 
 
 Repeating character classes and back references
@@ -321,10 +336,10 @@ if it is one of
   OP_CRRANGE
   OP_CRMINRANGE
 
-All but the last two are just single-byte items. The others are followed by
-four bytes of data, comprising the minimum and maximum repeat counts. There are 
-no special possessive opcodes for these repeats; a possessive repeat is 
-compiled into an atomic group.
+All but the last two are just single-unit items. The others are followed by
+four bytes (two shorts) of data, comprising the minimum and maximum repeat
+counts. There are no special possessive opcodes for these repeats; a possessive
+repeat is compiled into an atomic group.
 
 
 Brackets and alternation
@@ -334,7 +349,8 @@ A pair of non-capturing (round) brackets is wrapped round each expression at
 compile time, so alternation always happens in the context of brackets.
 
 [Note for North Americans: "bracket" to some English speakers, including
-myself, can be round, square, curly, or pointy. Hence this usage.]
+myself, can be round, square, curly, or pointy. Hence this usage rather than 
+"parentheses".]
 
 Non-capturing brackets use the opcode OP_BRA. Originally PCRE was limited to 99
 capturing brackets and it used a different opcode for each one. From release
@@ -346,9 +362,9 @@ A bracket opcode is followed by LINK_SIZE bytes which give the offset to the
 next alternative OP_ALT or, if there aren't any branches, to the matching
 OP_KET opcode. Each OP_ALT is followed by LINK_SIZE bytes giving the offset to
 the next one, or to the OP_KET opcode. For capturing brackets, the bracket 
-number immediately follows the offset, always as a 2-byte item.
+number immediately follows the offset, always as a 2-byte (one short) item.
 
-OP_KET is used for subpatterns that do not repeat indefinitely, while
+OP_KET is used for subpatterns that do not repeat indefinitely, and
 OP_KETRMIN and OP_KETRMAX are used for indefinite repetitions, minimally or
 maximally respectively (see below for possessive repetitions). All three are
 followed by LINK_SIZE bytes giving (as a positive number) the offset back to
@@ -356,7 +372,7 @@ the matching bracket opcode.
 
 If a subpattern is quantified such that it is permitted to match zero times, it
 is preceded by one of OP_BRAZERO, OP_BRAMINZERO, or OP_SKIPZERO. These are
-single-byte opcodes that tell the matcher that skipping the following
+single-unit opcodes that tell the matcher that skipping the following
 subpattern entirely is a valid branch. In the case of the first two, not 
 skipping the pattern is also valid (greedy and non-greedy). The third is used 
 when a pattern has the quantifier {0,0}. It cannot be entirely discarded, 
@@ -395,11 +411,11 @@ Assertions
 Forward assertions are just like other subpatterns, but starting with one of
 the opcodes OP_ASSERT or OP_ASSERT_NOT. Backward assertions use the opcodes
 OP_ASSERTBACK and OP_ASSERTBACK_NOT, and the first opcode inside the assertion
-is OP_REVERSE, followed by a two byte count of the number of characters to move
-back the pointer in the subject string. When operating in UTF-8 mode, the count
-is a character count rather than a byte count. A separate count is present in
-each alternative of a lookbehind assertion, allowing them to have different
-fixed lengths.
+is OP_REVERSE, followed by a two byte (one short) count of the number of
+characters to move back the pointer in the subject string. In ASCII mode, the 
+count is a number of units, but in UTF-8/16 mode each character may occupy more
+than one unit. A separate count is present in each alternative of a lookbehind
+assertion, allowing them to have different fixed lengths.
 
 
 Once-only (atomic) subpatterns
@@ -416,14 +432,15 @@ Conditional subpatterns
 These are like other subpatterns, but they start with the opcode OP_COND, or
 OP_SCOND for one that might match an empty string in an unbounded repeat. If
 the condition is a back reference, this is stored at the start of the
-subpattern using the opcode OP_CREF followed by two bytes containing the
-reference number. OP_NCREF is used instead if the reference was generated by 
-name (so that the runtime code knows to check for duplicate names).
+subpattern using the opcode OP_CREF followed by two bytes (one short)
+containing the reference number. OP_NCREF is used instead if the reference was
+generated by name (so that the runtime code knows to check for duplicate
+names).
 
 If the condition is "in recursion" (coded as "(?(R)"), or "in recursion of
 group x" (coded as "(?(Rx)"), the group number is stored at the start of the
 subpattern using the opcode OP_RREF or OP_NRREF (cf OP_NCREF), and a value of
-zero for "the whole pattern". For a DEFINE condition, just the single byte
+zero for "the whole pattern". For a DEFINE condition, just the single unit
 OP_DEF is used (it has no associated data). Otherwise, a conditional subpattern
 always starts with one of the assertions.
 
@@ -442,12 +459,12 @@ are not strictly a recursion.
 Callout
 -------
 
-OP_CALLOUT is followed by one byte of data that holds a callout number in the
+OP_CALLOUT is followed by one unit of data that holds a callout number in the
 range 0 to 254 for manual callouts, or 255 for an automatic callout. In both 
-cases there follows a two-byte value giving the offset in the pattern to the
-start of the following item, and another two-byte item giving the length of the
-next item.
+cases there follows a two-byte (one short) value giving the offset in the
+pattern to the start of the following item, and another two-byte (one short)
+item giving the length of the next item.
 
 
 Philip Hazel
-October 2011
+December 2011