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OVMS3/OVMS.V3/components/duktape/src-separate/duk_regexp_compiler.c

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/*
* Regexp compilation.
*
* See doc/regexp.rst for a discussion of the compilation approach and
* current limitations.
*
* Regexp bytecode assumes jumps can be expressed with signed 32-bit
* integers. Consequently the bytecode size must not exceed 0x7fffffffL.
* The implementation casts duk_size_t (buffer size) to duk_(u)int32_t
* in many places. Although this could be changed, the bytecode format
* limit would still prevent regexps exceeding the signed 32-bit limit
* from working.
*
* XXX: The implementation does not prevent bytecode from exceeding the
* maximum supported size. This could be done by limiting the maximum
* input string size (assuming an upper bound can be computed for number
* of bytecode bytes emitted per input byte) or checking buffer maximum
* size when emitting bytecode (slower).
*/
#include "duk_internal.h"
#if defined(DUK_USE_REGEXP_SUPPORT)
/*
* Helper macros
*/
#define DUK__RE_INITIAL_BUFSIZE 64
#define DUK__RE_BUFLEN(re_ctx) \
DUK_BW_GET_SIZE(re_ctx->thr, &re_ctx->bw)
/*
* Disjunction struct: result of parsing a disjunction
*/
typedef struct {
/* Number of characters that the atom matches (e.g. 3 for 'abc'),
* -1 if atom is complex and number of matched characters either
* varies or is not known.
*/
duk_int32_t charlen;
#if 0
/* These are not needed to implement quantifier capture handling,
* but might be needed at some point.
*/
/* re_ctx->captures at start and end of atom parsing.
* Since 'captures' indicates highest capture number emitted
* so far in a DUK_REOP_SAVE, the captures numbers saved by
* the atom are: ]start_captures,end_captures].
*/
duk_uint32_t start_captures;
duk_uint32_t end_captures;
#endif
} duk__re_disjunction_info;
/*
* Encoding helpers
*
* Some of the typing is bytecode based, e.g. slice sizes are unsigned 32-bit
* even though the buffer operations will use duk_size_t.
*/
/* XXX: the insert helpers should ensure that the bytecode result is not
* larger than expected (or at least assert for it). Many things in the
* bytecode, like skip offsets, won't work correctly if the bytecode is
* larger than say 2G.
*/
DUK_LOCAL duk_uint32_t duk__encode_i32(duk_int32_t x) {
if (x < 0) {
return ((duk_uint32_t) (-x)) * 2 + 1;
} else {
return ((duk_uint32_t) x) * 2;
}
}
/* XXX: return type should probably be duk_size_t, or explicit checks are needed for
* maximum size.
*/
DUK_LOCAL duk_uint32_t duk__insert_u32(duk_re_compiler_ctx *re_ctx, duk_uint32_t offset, duk_uint32_t x) {
duk_uint8_t buf[DUK_UNICODE_MAX_XUTF8_LENGTH];
duk_small_int_t len;
len = duk_unicode_encode_xutf8((duk_ucodepoint_t) x, buf);
DUK_ASSERT(len >= 0);
DUK_BW_INSERT_ENSURE_BYTES(re_ctx->thr, &re_ctx->bw, offset, buf, (duk_size_t) len);
return (duk_uint32_t) len;
}
DUK_LOCAL void duk__append_u32(duk_re_compiler_ctx *re_ctx, duk_uint32_t x) {
DUK_BW_WRITE_ENSURE_XUTF8(re_ctx->thr, &re_ctx->bw, x);
}
DUK_LOCAL void duk__append_7bit(duk_re_compiler_ctx *re_ctx, duk_uint32_t x) {
#if defined(DUK_USE_PREFER_SIZE)
duk__append_u32(re_ctx, x);
#else
DUK_ASSERT(x <= 0x7fU);
DUK_BW_WRITE_ENSURE_U8(re_ctx->thr, &re_ctx->bw, (duk_uint8_t) x);
#endif
}
#if 0
DUK_LOCAL void duk__append_2bytes(duk_re_compiler_ctx *re_ctx, duk_uint8_t x, duk_uint8_t y) {
DUK_BW_WRITE_ENSURE_U8_2(re_ctx->thr, &re_ctx->bw, x, y);
}
#endif
DUK_LOCAL duk_uint32_t duk__insert_i32(duk_re_compiler_ctx *re_ctx, duk_uint32_t offset, duk_int32_t x) {
return duk__insert_u32(re_ctx, offset, duk__encode_i32(x));
}
DUK_LOCAL void duk__append_reop(duk_re_compiler_ctx *re_ctx, duk_uint32_t reop) {
DUK_ASSERT(reop <= 0x7fU);
(void) duk__append_7bit(re_ctx, reop);
}
#if 0 /* unused */
DUK_LOCAL void duk__append_i32(duk_re_compiler_ctx *re_ctx, duk_int32_t x) {
duk__append_u32(re_ctx, duk__encode_i32(x));
}
#endif
/* special helper for emitting u16 lists (used for character ranges for built-in char classes) */
DUK_LOCAL void duk__append_u16_list(duk_re_compiler_ctx *re_ctx, const duk_uint16_t *values, duk_uint32_t count) {
/* Call sites don't need the result length so it's not accumulated. */
while (count-- > 0) {
duk__append_u32(re_ctx, (duk_uint32_t) (*values++));
}
}
DUK_LOCAL void duk__insert_slice(duk_re_compiler_ctx *re_ctx, duk_uint32_t offset, duk_uint32_t data_offset, duk_uint32_t data_length) {
DUK_BW_INSERT_ENSURE_SLICE(re_ctx->thr, &re_ctx->bw, offset, data_offset, data_length);
}
DUK_LOCAL void duk__append_slice(duk_re_compiler_ctx *re_ctx, duk_uint32_t data_offset, duk_uint32_t data_length) {
DUK_BW_WRITE_ENSURE_SLICE(re_ctx->thr, &re_ctx->bw, data_offset, data_length);
}
DUK_LOCAL void duk__remove_slice(duk_re_compiler_ctx *re_ctx, duk_uint32_t data_offset, duk_uint32_t data_length) {
DUK_BW_REMOVE_ENSURE_SLICE(re_ctx->thr, &re_ctx->bw, data_offset, data_length);
}
/*
* Insert a jump offset at 'offset' to complete an instruction
* (the jump offset is always the last component of an instruction).
* The 'skip' argument must be computed relative to 'offset',
* -without- taking into account the skip field being inserted.
*
* ... A B C ins X Y Z ... (ins may be a JUMP, SPLIT1/SPLIT2, etc)
* => ... A B C ins SKIP X Y Z
*
* Computing the final (adjusted) skip value, which is relative to the
* first byte of the next instruction, is a bit tricky because of the
* variable length UTF-8 encoding. See doc/regexp.rst for discussion.
*/
DUK_LOCAL duk_uint32_t duk__insert_jump_offset(duk_re_compiler_ctx *re_ctx, duk_uint32_t offset, duk_int32_t skip) {
#if 0
/* Iterative solution. */
if (skip < 0) {
duk_small_int_t len;
/* two encoding attempts suffices */
len = duk_unicode_get_xutf8_length((duk_codepoint_t) duk__encode_i32(skip));
len = duk_unicode_get_xutf8_length((duk_codepoint_t) duk__encode_i32(skip - (duk_int32_t) len));
DUK_ASSERT(duk_unicode_get_xutf8_length(duk__encode_i32(skip - (duk_int32_t) len)) == len); /* no change */
skip -= (duk_int32_t) len;
}
#endif
#if defined(DUK_USE_PREFER_SIZE)
/* Closed form solution, this produces smallest code.
* See re_neg_jump_offset (closed2).
*/
if (skip < 0) {
skip--;
if (skip < -0x3fL) {
skip--;
}
if (skip < -0x3ffL) {
skip--;
}
if (skip < -0x7fffL) {
skip--;
}
if (skip < -0xfffffL) {
skip--;
}
if (skip < -0x1ffffffL) {
skip--;
}
if (skip < -0x3fffffffL) {
skip--;
}
}
#else /* DUK_USE_PREFER_SIZE */
/* Closed form solution, this produces fastest code.
* See re_neg_jump_offset (closed1).
*/
if (skip < 0) {
if (skip >= -0x3eL) {
skip -= 1;
} else if (skip >= -0x3fdL) {
skip -= 2;
} else if (skip >= -0x7ffcL) {
skip -= 3;
} else if (skip >= -0xffffbL) {
skip -= 4;
} else if (skip >= -0x1fffffaL) {
skip -= 5;
} else if (skip >= -0x3ffffff9L) {
skip -= 6;
} else {
skip -= 7;
}
}
#endif /* DUK_USE_PREFER_SIZE */
return duk__insert_i32(re_ctx, offset, skip);
}
DUK_LOCAL duk_uint32_t duk__append_jump_offset(duk_re_compiler_ctx *re_ctx, duk_int32_t skip) {
return (duk_uint32_t) duk__insert_jump_offset(re_ctx, (duk_uint32_t) DUK__RE_BUFLEN(re_ctx), skip);
}
/*
* duk_re_range_callback for generating character class ranges.
*
* When ignoreCase is false, the range is simply emitted as is. We don't,
* for instance, eliminate duplicates or overlapping ranges in a character
* class.
*
* When ignoreCase is true but the 'direct' flag is set, the caller knows
* that the range canonicalizes to itself for case insensitive matching,
* so the range is emitted as is. This is mainly useful for built-in ranges
* like \W.
*
* Otherwise, when ignoreCase is true, the range needs to be normalized
* through canonicalization. Unfortunately a canonicalized version of a
* continuous range is not necessarily continuous (e.g. [x-{] is continuous
* but [X-{] is not). As a result, a single input range may expand to a lot
* of output ranges. The current algorithm creates the canonicalized ranges
* footprint efficiently at the cost of compile time execution time; see
* doc/regexp.rst for discussion, and some more details below.
*
* Note that the ctx->nranges is a context-wide temporary value. This is OK
* because there cannot be multiple character classes being parsed
* simultaneously.
*
* More detail on canonicalization:
*
* Conceptually, a range is canonicalized by scanning the entire range,
* normalizing each codepoint by converting it to uppercase, and generating
* a set of result ranges.
*
* Ideally a minimal set of output ranges would be emitted by merging all
* possible ranges even if they're emitted out of sequence. Because the
* input string is also case normalized during matching, some codepoints
* never occur at runtime; these "don't care" codepoints can be included or
* excluded from ranges when merging/optimizing ranges.
*
* The current algorithm does not do optimal range merging. Rather, output
* codepoints are generated in sequence, and when the output codepoints are
* continuous (CP, CP+1, CP+2, ...), they are merged locally into as large a
* range as possible. A small canonicalization bitmap is used to reduce
* actual codepoint canonicalizations which are quite slow at present. The
* bitmap provides a "codepoint block is continuous with respect to
* canonicalization" for N-codepoint blocks. This allows blocks to be
* skipped quickly.
*
* There are a number of shortcomings and future work here:
*
* - Individual codepoint normalizations are slow because they involve
* walking bit-packed rules without a lookup index.
*
* - The conceptual algorithm needs to canonicalize every codepoint in the
* input range to figure out the output range(s). Even with the small
* canonicalization bitmap the algorithm runs quite slowly for worst case
* inputs. There are many data structure alternatives to improve this.
*
* - While the current algorithm generates maximal output ranges when the
* output codepoints are emitted linearly, output ranges are not sorted or
* merged otherwise. In the worst case a lot of ranges are emitted when
* most of the ranges could be merged. In this process one could take
* advantage of "don't care" codepoints, which are never matched against at
* runtime due to canonicalization of input codepoints before comparison,
* to merge otherwise discontinuous output ranges.
*
* - The runtime data structure is just a linear list of ranges to match
* against. This can be quite slow if there are a lot of output ranges.
* There are various ways to make matching against the ranges faster,
* e.g. sorting the ranges and using a binary search; skip lists; tree
* based representations; full or approximate codepoint bitmaps, etc.
*
* - Only BMP is supported, codepoints above BMP are assumed to canonicalize
* to themselves. For now this is one place where we don't want to
* support chars outside the BMP, because the exhaustive search would be
* massively larger. It would be possible to support non-BMP with a
* different algorithm, or perhaps doing case normalization only at match
* time.
*/
DUK_LOCAL void duk__regexp_emit_range(duk_re_compiler_ctx *re_ctx, duk_codepoint_t r1, duk_codepoint_t r2) {
DUK_ASSERT(r2 >= r1);
duk__append_u32(re_ctx, (duk_uint32_t) r1);
duk__append_u32(re_ctx, (duk_uint32_t) r2);
re_ctx->nranges++;
}
#if defined(DUK_USE_REGEXP_CANON_BITMAP)
/* Find next canonicalization discontinuity (conservative estimate) starting
* from 'start', not exceeding 'end'. If continuity is fine up to 'end'
* inclusive, returns end. Minimum possible return value is start.
*/
DUK_LOCAL duk_codepoint_t duk__re_canon_next_discontinuity(duk_codepoint_t start, duk_codepoint_t end) {
duk_uint_t start_blk;
duk_uint_t end_blk;
duk_uint_t blk;
duk_uint_t offset;
duk_uint8_t mask;
/* Inclusive block range. */
DUK_ASSERT(start >= 0);
DUK_ASSERT(end >= 0);
DUK_ASSERT(end >= start);
start_blk = (duk_uint_t) (start >> DUK_CANON_BITMAP_BLKSHIFT);
end_blk = (duk_uint_t) (end >> DUK_CANON_BITMAP_BLKSHIFT);
for (blk = start_blk; blk <= end_blk; blk++) {
offset = blk >> 3;
mask = 1U << (blk & 0x07);
if (offset >= sizeof(duk_unicode_re_canon_bitmap)) {
/* Reached non-BMP range which is assumed continuous. */
return end;
}
DUK_ASSERT(offset < sizeof(duk_unicode_re_canon_bitmap));
if ((duk_unicode_re_canon_bitmap[offset] & mask) == 0) {
/* Block is discontinuous, continuity is guaranteed
* only up to end of previous block (+1 for exclusive
* return value => start of current block). Start
* block requires special handling.
*/
if (blk > start_blk) {
return (duk_codepoint_t) (blk << DUK_CANON_BITMAP_BLKSHIFT);
} else {
return start;
}
}
}
DUK_ASSERT(blk == end_blk + 1); /* Reached end block which is continuous. */
return end;
}
#else /* DUK_USE_REGEXP_CANON_BITMAP */
DUK_LOCAL duk_codepoint_t duk__re_canon_next_discontinuity(duk_codepoint_t start, duk_codepoint_t end) {
DUK_ASSERT(start >= 0);
DUK_ASSERT(end >= 0);
DUK_ASSERT(end >= start);
if (start >= 0x10000) {
/* Even without the bitmap, treat non-BMP as continuous. */
return end;
}
return start;
}
#endif /* DUK_USE_REGEXP_CANON_BITMAP */
DUK_LOCAL void duk__regexp_generate_ranges(void *userdata, duk_codepoint_t r1, duk_codepoint_t r2, duk_bool_t direct) {
duk_re_compiler_ctx *re_ctx = (duk_re_compiler_ctx *) userdata;
duk_codepoint_t r_start;
duk_codepoint_t r_end;
duk_codepoint_t i;
duk_codepoint_t t;
duk_codepoint_t r_disc;
DUK_DD(DUK_DDPRINT("duk__regexp_generate_ranges(): re_ctx=%p, range=[%ld,%ld] direct=%ld",
(void *) re_ctx, (long) r1, (long) r2, (long) direct));
DUK_ASSERT(r2 >= r1); /* SyntaxError for out of order range. */
if (direct || (re_ctx->re_flags & DUK_RE_FLAG_IGNORE_CASE) == 0) {
DUK_DD(DUK_DDPRINT("direct or not case sensitive, emit range: [%ld,%ld]", (long) r1, (long) r2));
duk__regexp_emit_range(re_ctx, r1, r2);
return;
}
DUK_DD(DUK_DDPRINT("case sensitive, process range: [%ld,%ld]", (long) r1, (long) r2));
r_start = duk_unicode_re_canonicalize_char(re_ctx->thr, r1);
r_end = r_start;
for (i = r1 + 1; i <= r2;) {
/* Input codepoint space processed up to i-1, and
* current range in r_{start,end} is up-to-date
* (inclusive) and may either break or continue.
*/
r_disc = duk__re_canon_next_discontinuity(i, r2);
DUK_ASSERT(r_disc >= i);
DUK_ASSERT(r_disc <= r2);
r_end += r_disc - i; /* May be zero. */
t = duk_unicode_re_canonicalize_char(re_ctx->thr, r_disc);
if (t == r_end + 1) {
/* Not actually a discontinuity, continue range
* to r_disc and recheck.
*/
r_end = t;
} else {
duk__regexp_emit_range(re_ctx, r_start, r_end);
r_start = t;
r_end = t;
}
i = r_disc + 1; /* Guarantees progress. */
}
duk__regexp_emit_range(re_ctx, r_start, r_end);
#if 0 /* Exhaustive search, very slow. */
r_start = duk_unicode_re_canonicalize_char(re_ctx->thr, r1);
r_end = r_start;
for (i = r1 + 1; i <= r2; i++) {
t = duk_unicode_re_canonicalize_char(re_ctx->thr, i);
if (t == r_end + 1) {
r_end = t;
} else {
DUK_DD(DUK_DDPRINT("canonicalized, emit range: [%ld,%ld]", (long) r_start, (long) r_end));
duk__append_u32(re_ctx, (duk_uint32_t) r_start);
duk__append_u32(re_ctx, (duk_uint32_t) r_end);
re_ctx->nranges++;
r_start = t;
r_end = t;
}
}
DUK_DD(DUK_DDPRINT("canonicalized, emit range: [%ld,%ld]", (long) r_start, (long) r_end));
duk__append_u32(re_ctx, (duk_uint32_t) r_start);
duk__append_u32(re_ctx, (duk_uint32_t) r_end);
re_ctx->nranges++;
#endif
}
/*
* Parse regexp Disjunction. Most of regexp compilation happens here.
*
* Handles Disjunction, Alternative, and Term productions directly without
* recursion. The only constructs requiring recursion are positive/negative
* lookaheads, capturing parentheses, and non-capturing parentheses.
*
* The function determines whether the entire disjunction is a 'simple atom'
* (see doc/regexp.rst discussion on 'simple quantifiers') and if so,
* returns the atom character length which is needed by the caller to keep
* track of its own atom character length. A disjunction with more than one
* alternative is never considered a simple atom (although in some cases
* that might be the case).
*
* Return value: simple atom character length or < 0 if not a simple atom.
* Appends the bytecode for the disjunction matcher to the end of the temp
* buffer.
*
* Regexp top level structure is:
*
* Disjunction = Term*
* | Term* | Disjunction
*
* Term = Assertion
* | Atom
* | Atom Quantifier
*
* An empty Term sequence is a valid disjunction alternative (e.g. /|||c||/).
*
* Notes:
*
* * Tracking of the 'simple-ness' of the current atom vs. the entire
* disjunction are separate matters. For instance, the disjunction
* may be complex, but individual atoms may be simple. Furthermore,
* simple quantifiers are used whenever possible, even if the
* disjunction as a whole is complex.
*
* * The estimate of whether an atom is simple is conservative now,
* and it would be possible to expand it. For instance, captures
* cause the disjunction to be marked complex, even though captures
* -can- be handled by simple quantifiers with some minor modifications.
*
* * Disjunction 'tainting' as 'complex' is handled at the end of the
* main for loop collectively for atoms. Assertions, quantifiers,
* and '|' tokens need to taint the result manually if necessary.
* Assertions cannot add to result char length, only atoms (and
* quantifiers) can; currently quantifiers will taint the result
* as complex though.
*/
DUK_LOCAL const duk_uint16_t * const duk__re_range_lookup1[3] = {
duk_unicode_re_ranges_digit,
duk_unicode_re_ranges_white,
duk_unicode_re_ranges_wordchar
};
DUK_LOCAL const duk_uint8_t duk__re_range_lookup2[3] = {
sizeof(duk_unicode_re_ranges_digit) / (2 * sizeof(duk_uint16_t)),
sizeof(duk_unicode_re_ranges_white) / (2 * sizeof(duk_uint16_t)),
sizeof(duk_unicode_re_ranges_wordchar) / (2 * sizeof(duk_uint16_t))
};
DUK_LOCAL void duk__append_range_atom_matcher(duk_re_compiler_ctx *re_ctx, duk_small_uint_t re_op, const duk_uint16_t *ranges, duk_small_uint_t count) {
#if 0
DUK_ASSERT(re_op <= 0x7fUL);
DUK_ASSERT(count <= 0x7fUL);
duk__append_2bytes(re_ctx, (duk_uint8_t) re_op, (duk_uint8_t) count);
#endif
duk__append_reop(re_ctx, re_op);
duk__append_7bit(re_ctx, count);
duk__append_u16_list(re_ctx, ranges, count * 2);
}
DUK_LOCAL void duk__parse_disjunction(duk_re_compiler_ctx *re_ctx, duk_bool_t expect_eof, duk__re_disjunction_info *out_atom_info) {
duk_int32_t atom_start_offset = -1; /* negative -> no atom matched on previous round */
duk_int32_t atom_char_length = 0; /* negative -> complex atom */
duk_uint32_t atom_start_captures = re_ctx->captures; /* value of re_ctx->captures at start of atom */
duk_int32_t unpatched_disjunction_split = -1;
duk_int32_t unpatched_disjunction_jump = -1;
duk_uint32_t entry_offset = (duk_uint32_t) DUK__RE_BUFLEN(re_ctx);
duk_int32_t res_charlen = 0; /* -1 if disjunction is complex, char length if simple */
duk__re_disjunction_info tmp_disj;
DUK_ASSERT(out_atom_info != NULL);
duk_native_stack_check(re_ctx->thr);
if (re_ctx->recursion_depth >= re_ctx->recursion_limit) {
DUK_ERROR_RANGE(re_ctx->thr, DUK_STR_REGEXP_COMPILER_RECURSION_LIMIT);
DUK_WO_NORETURN(return;);
}
re_ctx->recursion_depth++;
#if 0
out_atom_info->start_captures = re_ctx->captures;
#endif
for (;;) {
/* atom_char_length, atom_start_offset, atom_start_offset reflect the
* atom matched on the previous loop. If a quantifier is encountered
* on this loop, these are needed to handle the quantifier correctly.
* new_atom_char_length etc are for the atom parsed on this round;
* they're written to atom_char_length etc at the end of the round.
*/
duk_int32_t new_atom_char_length; /* char length of the atom parsed in this loop */
duk_int32_t new_atom_start_offset; /* bytecode start offset of the atom parsed in this loop
* (allows quantifiers to copy the atom bytecode)
*/
duk_uint32_t new_atom_start_captures; /* re_ctx->captures at the start of the atom parsed in this loop */
duk_lexer_parse_re_token(&re_ctx->lex, &re_ctx->curr_token);
DUK_DD(DUK_DDPRINT("re token: %ld (num=%ld, char=%c)",
(long) re_ctx->curr_token.t,
(long) re_ctx->curr_token.num,
(re_ctx->curr_token.num >= 0x20 && re_ctx->curr_token.num <= 0x7e) ?
(int) re_ctx->curr_token.num : (int) '?'));
/* set by atom case clauses */
new_atom_start_offset = -1;
new_atom_char_length = -1;
new_atom_start_captures = re_ctx->captures;
switch (re_ctx->curr_token.t) {
case DUK_RETOK_DISJUNCTION: {
/*
* The handling here is a bit tricky. If a previous '|' has been processed,
* we have a pending split1 and a pending jump (for a previous match). These
* need to be back-patched carefully. See docs for a detailed example.
*/
/* patch pending jump and split */
if (unpatched_disjunction_jump >= 0) {
duk_uint32_t offset;
DUK_ASSERT(unpatched_disjunction_split >= 0);
offset = (duk_uint32_t) unpatched_disjunction_jump;
offset += duk__insert_jump_offset(re_ctx,
offset,
(duk_int32_t) (DUK__RE_BUFLEN(re_ctx) - offset));
/* offset is now target of the pending split (right after jump) */
duk__insert_jump_offset(re_ctx,
(duk_uint32_t) unpatched_disjunction_split,
(duk_int32_t) offset - unpatched_disjunction_split);
}
/* add a new pending split to the beginning of the entire disjunction */
(void) duk__insert_u32(re_ctx,
entry_offset,
DUK_REOP_SPLIT1); /* prefer direct execution */
unpatched_disjunction_split = (duk_int32_t) (entry_offset + 1); /* +1 for opcode */
/* add a new pending match jump for latest finished alternative */
duk__append_reop(re_ctx, DUK_REOP_JUMP);
unpatched_disjunction_jump = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
/* 'taint' result as complex */
res_charlen = -1;
break;
}
case DUK_RETOK_QUANTIFIER: {
if (atom_start_offset < 0) {
DUK_ERROR_SYNTAX(re_ctx->thr, DUK_STR_INVALID_QUANTIFIER_NO_ATOM);
DUK_WO_NORETURN(return;);
}
if (re_ctx->curr_token.qmin > re_ctx->curr_token.qmax) {
DUK_ERROR_SYNTAX(re_ctx->thr, DUK_STR_INVALID_QUANTIFIER_VALUES);
DUK_WO_NORETURN(return;);
}
if (atom_char_length >= 0) {
/*
* Simple atom
*
* If atom_char_length is zero, we'll have unbounded execution time for e.g.
* /()*x/.exec('x'). We can't just skip the match because it might have some
* side effects (for instance, if we allowed captures in simple atoms, the
* capture needs to happen). The simple solution below is to force the
* quantifier to match at most once, since the additional matches have no effect.
*
* With a simple atom there can be no capture groups, so no captures need
* to be reset.
*/
duk_int32_t atom_code_length;
duk_uint32_t offset;
duk_uint32_t qmin, qmax;
qmin = re_ctx->curr_token.qmin;
qmax = re_ctx->curr_token.qmax;
if (atom_char_length == 0) {
/* qmin and qmax will be 0 or 1 */
if (qmin > 1) {
qmin = 1;
}
if (qmax > 1) {
qmax = 1;
}
}
duk__append_reop(re_ctx, DUK_REOP_MATCH); /* complete 'sub atom' */
atom_code_length = (duk_int32_t) (DUK__RE_BUFLEN(re_ctx) - (duk_size_t) atom_start_offset);
offset = (duk_uint32_t) atom_start_offset;
if (re_ctx->curr_token.greedy) {
offset += duk__insert_u32(re_ctx, offset, DUK_REOP_SQGREEDY);
offset += duk__insert_u32(re_ctx, offset, qmin);
offset += duk__insert_u32(re_ctx, offset, qmax);
offset += duk__insert_u32(re_ctx, offset, (duk_uint32_t) atom_char_length);
offset += duk__insert_jump_offset(re_ctx, offset, atom_code_length);
} else {
offset += duk__insert_u32(re_ctx, offset, DUK_REOP_SQMINIMAL);
offset += duk__insert_u32(re_ctx, offset, qmin);
offset += duk__insert_u32(re_ctx, offset, qmax);
offset += duk__insert_jump_offset(re_ctx, offset, atom_code_length);
}
DUK_UNREF(offset); /* silence scan-build warning */
} else {
/*
* Complex atom
*
* The original code is used as a template, and removed at the end
* (this differs from the handling of simple quantifiers).
*
* NOTE: there is no current solution for empty atoms in complex
* quantifiers. This would need some sort of a 'progress' instruction.
*
* XXX: impose limit on maximum result size, i.e. atom_code_len * atom_copies?
*/
duk_int32_t atom_code_length;
duk_uint32_t atom_copies;
duk_uint32_t tmp_qmin, tmp_qmax;
/* pre-check how many atom copies we're willing to make (atom_copies not needed below) */
atom_copies = (re_ctx->curr_token.qmax == DUK_RE_QUANTIFIER_INFINITE) ?
re_ctx->curr_token.qmin : re_ctx->curr_token.qmax;
if (atom_copies > DUK_RE_MAX_ATOM_COPIES) {
DUK_ERROR_RANGE(re_ctx->thr, DUK_STR_QUANTIFIER_TOO_MANY_COPIES);
DUK_WO_NORETURN(return;);
}
/* wipe the capture range made by the atom (if any) */
DUK_ASSERT(atom_start_captures <= re_ctx->captures);
if (atom_start_captures != re_ctx->captures) {
DUK_ASSERT(atom_start_captures < re_ctx->captures);
DUK_DDD(DUK_DDDPRINT("must wipe ]atom_start_captures,re_ctx->captures]: ]%ld,%ld]",
(long) atom_start_captures, (long) re_ctx->captures));
/* insert (DUK_REOP_WIPERANGE, start, count) in reverse order so the order ends up right */
duk__insert_u32(re_ctx, (duk_uint32_t) atom_start_offset, (re_ctx->captures - atom_start_captures) * 2U);
duk__insert_u32(re_ctx, (duk_uint32_t) atom_start_offset, (atom_start_captures + 1) * 2);
duk__insert_u32(re_ctx, (duk_uint32_t) atom_start_offset, DUK_REOP_WIPERANGE);
} else {
DUK_DDD(DUK_DDDPRINT("no need to wipe captures: atom_start_captures == re_ctx->captures == %ld",
(long) atom_start_captures));
}
atom_code_length = (duk_int32_t) DUK__RE_BUFLEN(re_ctx) - atom_start_offset;
/* insert the required matches (qmin) by copying the atom */
tmp_qmin = re_ctx->curr_token.qmin;
tmp_qmax = re_ctx->curr_token.qmax;
while (tmp_qmin > 0) {
duk__append_slice(re_ctx, (duk_uint32_t) atom_start_offset, (duk_uint32_t) atom_code_length);
tmp_qmin--;
if (tmp_qmax != DUK_RE_QUANTIFIER_INFINITE) {
tmp_qmax--;
}
}
DUK_ASSERT(tmp_qmin == 0);
/* insert code for matching the remainder - infinite or finite */
if (tmp_qmax == DUK_RE_QUANTIFIER_INFINITE) {
/* reuse last emitted atom for remaining 'infinite' quantifier */
if (re_ctx->curr_token.qmin == 0) {
/* Special case: original qmin was zero so there is nothing
* to repeat. Emit an atom copy but jump over it here.
*/
duk__append_reop(re_ctx, DUK_REOP_JUMP);
duk__append_jump_offset(re_ctx, atom_code_length);
duk__append_slice(re_ctx, (duk_uint32_t) atom_start_offset, (duk_uint32_t) atom_code_length);
}
if (re_ctx->curr_token.greedy) {
duk__append_reop(re_ctx, DUK_REOP_SPLIT2); /* prefer jump */
} else {
duk__append_reop(re_ctx, DUK_REOP_SPLIT1); /* prefer direct */
}
duk__append_jump_offset(re_ctx, -atom_code_length - 1); /* -1 for opcode */
} else {
/*
* The remaining matches are emitted as sequence of SPLITs and atom
* copies; the SPLITs skip the remaining copies and match the sequel.
* This sequence needs to be emitted starting from the last copy
* because the SPLITs are variable length due to the variable length
* skip offset. This causes a lot of memory copying now.
*
* Example structure (greedy, match maximum # atoms):
*
* SPLIT1 LSEQ
* (atom)
* SPLIT1 LSEQ ; <- the byte length of this instruction is needed
* (atom) ; to encode the above SPLIT1 correctly
* ...
* LSEQ:
*/
duk_uint32_t offset = (duk_uint32_t) DUK__RE_BUFLEN(re_ctx);
while (tmp_qmax > 0) {
duk__insert_slice(re_ctx, offset, (duk_uint32_t) atom_start_offset, (duk_uint32_t) atom_code_length);
if (re_ctx->curr_token.greedy) {
duk__insert_u32(re_ctx, offset, DUK_REOP_SPLIT1); /* prefer direct */
} else {
duk__insert_u32(re_ctx, offset, DUK_REOP_SPLIT2); /* prefer jump */
}
duk__insert_jump_offset(re_ctx,
offset + 1, /* +1 for opcode */
(duk_int32_t) (DUK__RE_BUFLEN(re_ctx) - (offset + 1)));
tmp_qmax--;
}
}
/* remove the original 'template' atom */
duk__remove_slice(re_ctx, (duk_uint32_t) atom_start_offset, (duk_uint32_t) atom_code_length);
}
/* 'taint' result as complex */
res_charlen = -1;
break;
}
case DUK_RETOK_ASSERT_START: {
duk__append_reop(re_ctx, DUK_REOP_ASSERT_START);
break;
}
case DUK_RETOK_ASSERT_END: {
duk__append_reop(re_ctx, DUK_REOP_ASSERT_END);
break;
}
case DUK_RETOK_ASSERT_WORD_BOUNDARY: {
duk__append_reop(re_ctx, DUK_REOP_ASSERT_WORD_BOUNDARY);
break;
}
case DUK_RETOK_ASSERT_NOT_WORD_BOUNDARY: {
duk__append_reop(re_ctx, DUK_REOP_ASSERT_NOT_WORD_BOUNDARY);
break;
}
case DUK_RETOK_ASSERT_START_POS_LOOKAHEAD:
case DUK_RETOK_ASSERT_START_NEG_LOOKAHEAD: {
duk_uint32_t offset;
duk_uint32_t opcode = (re_ctx->curr_token.t == DUK_RETOK_ASSERT_START_POS_LOOKAHEAD) ?
DUK_REOP_LOOKPOS : DUK_REOP_LOOKNEG;
offset = (duk_uint32_t) DUK__RE_BUFLEN(re_ctx);
duk__parse_disjunction(re_ctx, 0, &tmp_disj);
duk__append_reop(re_ctx, DUK_REOP_MATCH);
(void) duk__insert_u32(re_ctx, offset, opcode);
(void) duk__insert_jump_offset(re_ctx,
offset + 1, /* +1 for opcode */
(duk_int32_t) (DUK__RE_BUFLEN(re_ctx) - (offset + 1)));
/* 'taint' result as complex -- this is conservative,
* as lookaheads do not backtrack.
*/
res_charlen = -1;
break;
}
case DUK_RETOK_ATOM_PERIOD: {
new_atom_char_length = 1;
new_atom_start_offset = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
duk__append_reop(re_ctx, DUK_REOP_PERIOD);
break;
}
case DUK_RETOK_ATOM_CHAR: {
/* Note: successive characters could be joined into string matches
* but this is not trivial (consider e.g. '/xyz+/); see docs for
* more discussion.
*
* No support for \u{H+} yet. While only BMP Unicode escapes are
* supported for RegExps at present, 'ch' may still be a non-BMP
* codepoint if it is decoded straight from source text UTF-8.
* There's no non-BMP support yet so this is handled simply by
* matching the non-BMP character (which is custom behavior).
*/
duk_uint32_t ch;
new_atom_char_length = 1;
new_atom_start_offset = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
duk__append_reop(re_ctx, DUK_REOP_CHAR);
ch = re_ctx->curr_token.num;
if (re_ctx->re_flags & DUK_RE_FLAG_IGNORE_CASE) {
ch = (duk_uint32_t) duk_unicode_re_canonicalize_char(re_ctx->thr, (duk_codepoint_t) ch);
}
duk__append_u32(re_ctx, ch);
break;
}
case DUK_RETOK_ATOM_DIGIT:
case DUK_RETOK_ATOM_NOT_DIGIT:
case DUK_RETOK_ATOM_WHITE:
case DUK_RETOK_ATOM_NOT_WHITE:
case DUK_RETOK_ATOM_WORD_CHAR:
case DUK_RETOK_ATOM_NOT_WORD_CHAR: {
duk_small_uint_t re_op;
duk_small_uint_t idx;
new_atom_char_length = 1;
new_atom_start_offset = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
DUK_ASSERT((DUK_RETOK_ATOM_DIGIT & 0x01) != 0);
DUK_ASSERT((DUK_RETOK_ATOM_WHITE & 0x01) != 0);
DUK_ASSERT((DUK_RETOK_ATOM_WORD_CHAR & 0x01) != 0);
DUK_ASSERT((DUK_RETOK_ATOM_NOT_DIGIT & 0x01) == 0);
DUK_ASSERT((DUK_RETOK_ATOM_NOT_WHITE & 0x01) == 0);
DUK_ASSERT((DUK_RETOK_ATOM_NOT_WORD_CHAR & 0x01) == 0);
re_op = (re_ctx->curr_token.t & 0x01) ? DUK_REOP_RANGES : DUK_REOP_INVRANGES;
DUK_ASSERT(DUK_RETOK_ATOM_WHITE == DUK_RETOK_ATOM_DIGIT + 2);
DUK_ASSERT(DUK_RETOK_ATOM_WORD_CHAR == DUK_RETOK_ATOM_DIGIT + 4);
idx = (duk_small_uint_t) ((re_ctx->curr_token.t - DUK_RETOK_ATOM_DIGIT) >> 1U);
DUK_ASSERT(idx <= 2U); /* Assume continuous token numbers; also checks negative underflow. */
duk__append_range_atom_matcher(re_ctx, re_op, duk__re_range_lookup1[idx], duk__re_range_lookup2[idx]);
break;
}
case DUK_RETOK_ATOM_BACKREFERENCE: {
duk_uint32_t backref = (duk_uint32_t) re_ctx->curr_token.num;
if (backref > re_ctx->highest_backref) {
re_ctx->highest_backref = backref;
}
new_atom_char_length = -1; /* mark as complex */
new_atom_start_offset = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
duk__append_reop(re_ctx, DUK_REOP_BACKREFERENCE);
duk__append_u32(re_ctx, backref);
break;
}
case DUK_RETOK_ATOM_START_CAPTURE_GROUP: {
duk_uint32_t cap;
new_atom_char_length = -1; /* mark as complex (capture handling) */
new_atom_start_offset = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
cap = ++re_ctx->captures;
duk__append_reop(re_ctx, DUK_REOP_SAVE);
duk__append_u32(re_ctx, cap * 2);
duk__parse_disjunction(re_ctx, 0, &tmp_disj); /* retval (sub-atom char length) unused, tainted as complex above */
duk__append_reop(re_ctx, DUK_REOP_SAVE);
duk__append_u32(re_ctx, cap * 2 + 1);
break;
}
case DUK_RETOK_ATOM_START_NONCAPTURE_GROUP: {
new_atom_start_offset = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
duk__parse_disjunction(re_ctx, 0, &tmp_disj);
new_atom_char_length = tmp_disj.charlen;
break;
}
case DUK_RETOK_ATOM_START_CHARCLASS:
case DUK_RETOK_ATOM_START_CHARCLASS_INVERTED: {
/*
* Range parsing is done with a special lexer function which calls
* us for every range parsed. This is different from how rest of
* the parsing works, but avoids a heavy, arbitrary size intermediate
* value type to hold the ranges.
*
* Another complication is the handling of character ranges when
* case insensitive matching is used (see docs for discussion).
* The range handler callback given to the lexer takes care of this
* as well.
*
* Note that duplicate ranges are not eliminated when parsing character
* classes, so that canonicalization of
*
* [0-9a-fA-Fx-{]
*
* creates the result (note the duplicate ranges):
*
* [0-9A-FA-FX-Z{-{]
*
* where [x-{] is split as a result of canonicalization. The duplicate
* ranges are not a semantics issue: they work correctly.
*/
duk_uint32_t offset;
DUK_DD(DUK_DDPRINT("character class"));
/* insert ranges instruction, range count patched in later */
new_atom_char_length = 1;
new_atom_start_offset = (duk_int32_t) DUK__RE_BUFLEN(re_ctx);
duk__append_reop(re_ctx,
(re_ctx->curr_token.t == DUK_RETOK_ATOM_START_CHARCLASS) ?
DUK_REOP_RANGES : DUK_REOP_INVRANGES);
offset = (duk_uint32_t) DUK__RE_BUFLEN(re_ctx); /* patch in range count later */
/* parse ranges until character class ends */
re_ctx->nranges = 0; /* note: ctx-wide temporary */
duk_lexer_parse_re_ranges(&re_ctx->lex, duk__regexp_generate_ranges, (void *) re_ctx);
/* insert range count */
duk__insert_u32(re_ctx, offset, re_ctx->nranges);
break;
}
case DUK_RETOK_ATOM_END_GROUP: {
if (expect_eof) {
DUK_ERROR_SYNTAX(re_ctx->thr, DUK_STR_UNEXPECTED_CLOSING_PAREN);
DUK_WO_NORETURN(return;);
}
goto done;
}
case DUK_RETOK_EOF: {
if (!expect_eof) {
DUK_ERROR_SYNTAX(re_ctx->thr, DUK_STR_UNEXPECTED_END_OF_PATTERN);
DUK_WO_NORETURN(return;);
}
goto done;
}
default: {
DUK_ERROR_SYNTAX(re_ctx->thr, DUK_STR_UNEXPECTED_REGEXP_TOKEN);
DUK_WO_NORETURN(return;);
}
}
/* a complex (new) atom taints the result */
if (new_atom_start_offset >= 0) {
if (new_atom_char_length < 0) {
res_charlen = -1;
} else if (res_charlen >= 0) {
/* only advance if not tainted */
res_charlen += new_atom_char_length;
}
}
/* record previous atom info in case next token is a quantifier */
atom_start_offset = new_atom_start_offset;
atom_char_length = new_atom_char_length;
atom_start_captures = new_atom_start_captures;
}
done:
/* finish up pending jump and split for last alternative */
if (unpatched_disjunction_jump >= 0) {
duk_uint32_t offset;
DUK_ASSERT(unpatched_disjunction_split >= 0);
offset = (duk_uint32_t) unpatched_disjunction_jump;
offset += duk__insert_jump_offset(re_ctx,
offset,
(duk_int32_t) (DUK__RE_BUFLEN(re_ctx) - offset));
/* offset is now target of the pending split (right after jump) */
duk__insert_jump_offset(re_ctx,
(duk_uint32_t) unpatched_disjunction_split,
(duk_int32_t) offset - unpatched_disjunction_split);
}
#if 0
out_atom_info->end_captures = re_ctx->captures;
#endif
out_atom_info->charlen = res_charlen;
DUK_DDD(DUK_DDDPRINT("parse disjunction finished: charlen=%ld",
(long) out_atom_info->charlen));
re_ctx->recursion_depth--;
}
/*
* Flags parsing (see E5 Section 15.10.4.1).
*/
DUK_LOCAL duk_uint32_t duk__parse_regexp_flags(duk_hthread *thr, duk_hstring *h) {
const duk_uint8_t *p;
const duk_uint8_t *p_end;
duk_uint32_t flags = 0;
p = DUK_HSTRING_GET_DATA(h);
p_end = p + DUK_HSTRING_GET_BYTELEN(h);
/* Note: can be safely scanned as bytes (undecoded) */
while (p < p_end) {
duk_uint8_t c = *p++;
switch (c) {
case (duk_uint8_t) 'g': {
if (flags & DUK_RE_FLAG_GLOBAL) {
goto flags_error;
}
flags |= DUK_RE_FLAG_GLOBAL;
break;
}
case (duk_uint8_t) 'i': {
if (flags & DUK_RE_FLAG_IGNORE_CASE) {
goto flags_error;
}
flags |= DUK_RE_FLAG_IGNORE_CASE;
break;
}
case (duk_uint8_t) 'm': {
if (flags & DUK_RE_FLAG_MULTILINE) {
goto flags_error;
}
flags |= DUK_RE_FLAG_MULTILINE;
break;
}
default: {
goto flags_error;
}
}
}
return flags;
flags_error:
DUK_ERROR_SYNTAX(thr, DUK_STR_INVALID_REGEXP_FLAGS);
DUK_WO_NORETURN(return 0U;);
}
/*
* Create escaped RegExp source (E5 Section 15.10.3).
*
* The current approach is to special case the empty RegExp
* ('' -> '(?:)') and otherwise replace unescaped '/' characters
* with '\/' regardless of where they occur in the regexp.
*
* Note that normalization does not seem to be necessary for
* RegExp literals (e.g. '/foo/') because to be acceptable as
* a RegExp literal, the text between forward slashes must
* already match the escaping requirements (e.g. must not contain
* unescaped forward slashes or be empty). Escaping IS needed
* for expressions like 'new Regexp("...", "")' however.
* Currently, we re-escape in either case.
*
* Also note that we process the source here in UTF-8 encoded
* form. This is correct, because any non-ASCII characters are
* passed through without change.
*/
DUK_LOCAL void duk__create_escaped_source(duk_hthread *thr, int idx_pattern) {
duk_hstring *h;
const duk_uint8_t *p;
duk_bufwriter_ctx bw_alloc;
duk_bufwriter_ctx *bw;
duk_uint8_t *q;
duk_size_t i, n;
duk_uint_fast8_t c_prev, c;
h = duk_known_hstring(thr, idx_pattern);
p = (const duk_uint8_t *) DUK_HSTRING_GET_DATA(h);
n = (duk_size_t) DUK_HSTRING_GET_BYTELEN(h);
if (n == 0) {
duk_push_literal(thr, "(?:)");
return;
}
bw = &bw_alloc;
DUK_BW_INIT_PUSHBUF(thr, bw, n);
q = DUK_BW_GET_PTR(thr, bw);
c_prev = (duk_uint_fast8_t) 0;
for (i = 0; i < n; i++) {
c = p[i];
q = DUK_BW_ENSURE_RAW(thr, bw, 2, q);
if (c == (duk_uint_fast8_t) '/' && c_prev != (duk_uint_fast8_t) '\\') {
/* Unescaped '/' ANYWHERE in the regexp (in disjunction,
* inside a character class, ...) => same escape works.
*/
*q++ = DUK_ASC_BACKSLASH;
}
*q++ = (duk_uint8_t) c;
c_prev = c;
}
DUK_BW_SETPTR_AND_COMPACT(thr, bw, q);
(void) duk_buffer_to_string(thr, -1); /* Safe if input is safe. */
/* [ ... escaped_source ] */
}
/*
* Exposed regexp compilation primitive.
*
* Sets up a regexp compilation context, and calls duk__parse_disjunction() to do the
* actual parsing. Handles generation of the compiled regexp header and the
* "boilerplate" capture of the matching substring (save 0 and 1). Also does some
* global level regexp checks after recursive compilation has finished.
*
* An escaped version of the regexp source, suitable for use as a RegExp instance
* 'source' property (see E5 Section 15.10.3), is also left on the stack.
*
* Input stack: [ pattern flags ]
* Output stack: [ bytecode escaped_source ] (both as strings)
*/
DUK_INTERNAL void duk_regexp_compile(duk_hthread *thr) {
duk_re_compiler_ctx re_ctx;
duk_lexer_point lex_point;
duk_hstring *h_pattern;
duk_hstring *h_flags;
duk__re_disjunction_info ign_disj;
DUK_ASSERT(thr != NULL);
/*
* Args validation
*/
/* TypeError if fails */
h_pattern = duk_require_hstring_notsymbol(thr, -2);
h_flags = duk_require_hstring_notsymbol(thr, -1);
/*
* Create normalized 'source' property (E5 Section 15.10.3).
*/
/* [ ... pattern flags ] */
duk__create_escaped_source(thr, -2);
/* [ ... pattern flags escaped_source ] */
/*
* Init compilation context
*/
/* [ ... pattern flags escaped_source buffer ] */
duk_memzero(&re_ctx, sizeof(re_ctx));
DUK_LEXER_INITCTX(&re_ctx.lex); /* duplicate zeroing, expect for (possible) NULL inits */
re_ctx.thr = thr;
re_ctx.lex.thr = thr;
re_ctx.lex.input = DUK_HSTRING_GET_DATA(h_pattern);
re_ctx.lex.input_length = DUK_HSTRING_GET_BYTELEN(h_pattern);
re_ctx.lex.token_limit = DUK_RE_COMPILE_TOKEN_LIMIT;
re_ctx.recursion_limit = DUK_USE_REGEXP_COMPILER_RECLIMIT;
re_ctx.re_flags = duk__parse_regexp_flags(thr, h_flags);
DUK_BW_INIT_PUSHBUF(thr, &re_ctx.bw, DUK__RE_INITIAL_BUFSIZE);
DUK_DD(DUK_DDPRINT("regexp compiler ctx initialized, flags=0x%08lx, recursion_limit=%ld",
(unsigned long) re_ctx.re_flags, (long) re_ctx.recursion_limit));
/*
* Init lexer
*/
lex_point.offset = 0; /* expensive init, just want to fill window */
lex_point.line = 1;
DUK_LEXER_SETPOINT(&re_ctx.lex, &lex_point);
/*
* Compilation
*/
DUK_DD(DUK_DDPRINT("starting regexp compilation"));
duk__append_reop(&re_ctx, DUK_REOP_SAVE);
duk__append_7bit(&re_ctx, 0);
duk__parse_disjunction(&re_ctx, 1 /*expect_eof*/, &ign_disj);
duk__append_reop(&re_ctx, DUK_REOP_SAVE);
duk__append_7bit(&re_ctx, 1);
duk__append_reop(&re_ctx, DUK_REOP_MATCH);
/*
* Check for invalid backreferences; note that it is NOT an error
* to back-reference a capture group which has not yet been introduced
* in the pattern (as in /\1(foo)/); in fact, the backreference will
* always match! It IS an error to back-reference a capture group
* which will never be introduced in the pattern. Thus, we can check
* for such references only after parsing is complete.
*/
if (re_ctx.highest_backref > re_ctx.captures) {
DUK_ERROR_SYNTAX(thr, DUK_STR_INVALID_BACKREFS);
DUK_WO_NORETURN(return;);
}
/*
* Emit compiled regexp header: flags, ncaptures
* (insertion order inverted on purpose)
*/
duk__insert_u32(&re_ctx, 0, (re_ctx.captures + 1) * 2);
duk__insert_u32(&re_ctx, 0, re_ctx.re_flags);
/* [ ... pattern flags escaped_source buffer ] */
DUK_BW_COMPACT(thr, &re_ctx.bw);
(void) duk_buffer_to_string(thr, -1); /* Safe because flags is at most 7 bit. */
/* [ ... pattern flags escaped_source bytecode ] */
/*
* Finalize stack
*/
duk_remove(thr, -4); /* -> [ ... flags escaped_source bytecode ] */
duk_remove(thr, -3); /* -> [ ... escaped_source bytecode ] */
DUK_DD(DUK_DDPRINT("regexp compilation successful, bytecode: %!T, escaped source: %!T",
(duk_tval *) duk_get_tval(thr, -1), (duk_tval *) duk_get_tval(thr, -2)));
}
/*
* Create a RegExp instance (E5 Section 15.10.7).
*
* Note: the output stack left by duk_regexp_compile() is directly compatible
* with the input here.
*
* Input stack: [ escaped_source bytecode ] (both as strings)
* Output stack: [ RegExp ]
*/
DUK_INTERNAL void duk_regexp_create_instance(duk_hthread *thr) {
duk_hobject *h;
/* [ ... escaped_source bytecode ] */
duk_push_object(thr);
h = duk_known_hobject(thr, -1);
duk_insert(thr, -3);
/* [ ... regexp_object escaped_source bytecode ] */
DUK_HOBJECT_SET_CLASS_NUMBER(h, DUK_HOBJECT_CLASS_REGEXP);
DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, h, thr->builtins[DUK_BIDX_REGEXP_PROTOTYPE]);
duk_xdef_prop_stridx_short(thr, -3, DUK_STRIDX_INT_BYTECODE, DUK_PROPDESC_FLAGS_NONE);
/* [ ... regexp_object escaped_source ] */
/* In ES2015 .source, and the .global, .multiline, etc flags are
* inherited getters. Store the escaped source as an internal
* property for the getter.
*/
duk_xdef_prop_stridx_short(thr, -2, DUK_STRIDX_INT_SOURCE, DUK_PROPDESC_FLAGS_NONE);
/* [ ... regexp_object ] */
duk_push_int(thr, 0);
duk_xdef_prop_stridx_short(thr, -2, DUK_STRIDX_LAST_INDEX, DUK_PROPDESC_FLAGS_W);
/* [ ... regexp_object ] */
}
#else /* DUK_USE_REGEXP_SUPPORT */
/* regexp support disabled */
#endif /* DUK_USE_REGEXP_SUPPORT */
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