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janet/src/core/peg.c
Calvin Rose 3894f4021a Update copyright date.
2024-09-29 16:07:24 -05:00

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/*
* Copyright (c) 2024 Calvin Rose
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#ifndef JANET_AMALG
#include "features.h"
#include <janet.h>
#include <string.h>
#include "util.h"
#include "vector.h"
#include "util.h"
#endif
#ifdef JANET_PEG
/*
* Runtime
*/
/* Hold captured patterns and match state */
typedef struct {
const uint8_t *text_start;
const uint8_t *text_end;
/* text_end can be restricted by some rules, but
outer_text_end will always contain the real end of
input, which we need to generate a line mapping */
const uint8_t *outer_text_end;
const uint32_t *bytecode;
const Janet *constants;
JanetArray *captures;
JanetBuffer *scratch;
JanetBuffer *tags;
JanetArray *tagged_captures;
const Janet *extrav;
int32_t *linemap;
int32_t extrac;
int32_t depth;
int32_t linemaplen;
int32_t has_backref;
enum {
PEG_MODE_NORMAL,
PEG_MODE_ACCUMULATE
} mode;
} PegState;
/* Allow backtrack with captures. We need
* to save state at branches, and then reload
* if one branch fails and try a new branch. */
typedef struct {
int32_t cap;
int32_t tcap;
int32_t scratch;
} CapState;
/* Save the current capture state */
static CapState cap_save(PegState *s) {
CapState cs;
cs.scratch = s->scratch->count;
cs.cap = s->captures->count;
cs.tcap = s->tagged_captures->count;
return cs;
}
/* Load a saved capture state in the case of failure */
static void cap_load(PegState *s, CapState cs) {
s->scratch->count = cs.scratch;
s->captures->count = cs.cap;
s->tags->count = cs.tcap;
s->tagged_captures->count = cs.tcap;
}
/* Load a saved capture state in the case of success. Keeps
* tagged captures around for backref. */
static void cap_load_keept(PegState *s, CapState cs) {
s->scratch->count = cs.scratch;
s->captures->count = cs.cap;
}
/* Add a capture */
static void pushcap(PegState *s, Janet capture, uint32_t tag) {
if (s->mode == PEG_MODE_ACCUMULATE) {
janet_to_string_b(s->scratch, capture);
}
if (s->mode == PEG_MODE_NORMAL) {
janet_array_push(s->captures, capture);
}
if (s->has_backref) {
janet_array_push(s->tagged_captures, capture);
janet_buffer_push_u8(s->tags, tag);
}
}
/* Lazily generate line map to get line and column information for PegState.
* line and column are 1-indexed. */
typedef struct {
int32_t line;
int32_t col;
} LineCol;
static LineCol get_linecol_from_position(PegState *s, int32_t position) {
/* Generate if not made yet */
if (s->linemaplen < 0) {
int32_t newline_count = 0;
for (const uint8_t *c = s->text_start; c < s->outer_text_end; c++) {
if (*c == '\n') newline_count++;
}
int32_t *mem = janet_smalloc(sizeof(int32_t) * newline_count);
size_t index = 0;
for (const uint8_t *c = s->text_start; c < s->outer_text_end; c++) {
if (*c == '\n') mem[index++] = (int32_t)(c - s->text_start);
}
s->linemaplen = newline_count;
s->linemap = mem;
}
/* Do binary search for line. Slightly modified from classic binary search:
* - if we find that our current character is a line break, just return immediately.
* a newline character is consider to be on the same line as the character before
* (\n is line terminator, not line separator).
* - in the not-found case, we still want to find the greatest-indexed newline that
* is before position. we use that to calculate the line and column.
* - in the case that lo = 0 and s->linemap[0] is still greater than position, we
* are on the first line and our column is position + 1. */
int32_t hi = s->linemaplen; /* hi is greater than the actual line */
int32_t lo = 0; /* lo is less than or equal to the actual line */
LineCol ret;
while (lo + 1 < hi) {
int32_t mid = lo + (hi - lo) / 2;
if (s->linemap[mid] >= position) {
hi = mid;
} else {
lo = mid;
}
}
/* first line case */
if (s->linemaplen == 0 || (lo == 0 && s->linemap[0] >= position)) {
ret.line = 1;
ret.col = position + 1;
} else {
ret.line = lo + 2;
ret.col = position - s->linemap[lo];
}
return ret;
}
/* Convert a uint64_t to a int64_t by wrapping to a maximum number of bytes */
static int64_t peg_convert_u64_s64(uint64_t from, int width) {
int shift = 8 * (8 - width);
return ((int64_t)(from << shift)) >> shift;
}
/* Prevent stack overflow */
#define down1(s) do { \
if (0 == --((s)->depth)) janet_panic("peg/match recursed too deeply"); \
} while (0)
#define up1(s) ((s)->depth++)
/* Evaluate a peg rule
* Pre-conditions: s is in a valid state
* Post-conditions: If there is a match, returns a pointer to the next text.
* All captures on the capture stack are valid. If there is no match,
* returns NULL. Extra captures from successful child expressions can be
* left on the capture stack.
*/
static const uint8_t *peg_rule(
PegState *s,
const uint32_t *rule,
const uint8_t *text) {
tail:
switch (*rule) {
default:
janet_panic("unexpected opcode");
return NULL;
case RULE_LITERAL: {
uint32_t len = rule[1];
if (text + len > s->text_end) return NULL;
return memcmp(text, rule + 2, len) ? NULL : text + len;
}
case RULE_NCHAR: {
uint32_t n = rule[1];
return (text + n > s->text_end) ? NULL : text + n;
}
case RULE_NOTNCHAR: {
uint32_t n = rule[1];
return (text + n > s->text_end) ? text : NULL;
}
case RULE_RANGE: {
uint8_t lo = rule[1] & 0xFF;
uint8_t hi = (rule[1] >> 16) & 0xFF;
return (text < s->text_end &&
text[0] >= lo &&
text[0] <= hi)
? text + 1
: NULL;
}
case RULE_SET: {
if (text >= s->text_end) return NULL;
uint32_t word = rule[1 + (text[0] >> 5)];
uint32_t mask = (uint32_t)1 << (text[0] & 0x1F);
return (word & mask)
? text + 1
: NULL;
}
case RULE_LOOK: {
text += ((int32_t *)rule)[1];
if (text < s->text_start || text > s->text_end) return NULL;
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[2], text);
up1(s);
text -= ((int32_t *)rule)[1];
return result ? text : NULL;
}
case RULE_CHOICE: {
uint32_t len = rule[1];
const uint32_t *args = rule + 2;
if (len == 0) return NULL;
down1(s);
CapState cs = cap_save(s);
for (uint32_t i = 0; i < len - 1; i++) {
const uint8_t *result = peg_rule(s, s->bytecode + args[i], text);
if (result) {
up1(s);
return result;
}
cap_load(s, cs);
}
up1(s);
rule = s->bytecode + args[len - 1];
goto tail;
}
case RULE_SEQUENCE: {
uint32_t len = rule[1];
const uint32_t *args = rule + 2;
if (len == 0) return text;
down1(s);
for (uint32_t i = 0; text && i < len - 1; i++)
text = peg_rule(s, s->bytecode + args[i], text);
up1(s);
if (!text) return NULL;
rule = s->bytecode + args[len - 1];
goto tail;
}
case RULE_IF: {
const uint32_t *rule_a = s->bytecode + rule[1];
const uint32_t *rule_b = s->bytecode + rule[2];
down1(s);
const uint8_t *result = peg_rule(s, rule_a, text);
up1(s);
if (!result) return NULL;
rule = rule_b;
goto tail;
}
case RULE_IFNOT: {
const uint32_t *rule_a = s->bytecode + rule[1];
const uint32_t *rule_b = s->bytecode + rule[2];
down1(s);
CapState cs = cap_save(s);
const uint8_t *result = peg_rule(s, rule_a, text);
if (!!result) {
up1(s);
return NULL;
} else {
cap_load(s, cs);
up1(s);
rule = rule_b;
goto tail;
}
}
case RULE_NOT: {
const uint32_t *rule_a = s->bytecode + rule[1];
down1(s);
CapState cs = cap_save(s);
const uint8_t *result = peg_rule(s, rule_a, text);
if (result) {
up1(s);
return NULL;
} else {
cap_load(s, cs);
up1(s);
return text;
}
}
case RULE_THRU:
case RULE_TO: {
const uint32_t *rule_a = s->bytecode + rule[1];
const uint8_t *next_text = NULL;
CapState cs = cap_save(s);
down1(s);
while (text <= s->text_end) {
CapState cs2 = cap_save(s);
next_text = peg_rule(s, rule_a, text);
if (next_text) {
if (rule[0] == RULE_TO) cap_load(s, cs2);
break;
}
cap_load(s, cs2);
text++;
}
up1(s);
if (text > s->text_end) {
cap_load(s, cs);
return NULL;
}
return rule[0] == RULE_TO ? text : next_text;
}
case RULE_BETWEEN: {
uint32_t lo = rule[1];
uint32_t hi = rule[2];
const uint32_t *rule_a = s->bytecode + rule[3];
uint32_t captured = 0;
const uint8_t *next_text;
CapState cs = cap_save(s);
down1(s);
while (captured < hi) {
CapState cs2 = cap_save(s);
next_text = peg_rule(s, rule_a, text);
if (!next_text || next_text == text) {
cap_load(s, cs2);
break;
}
captured++;
text = next_text;
}
up1(s);
if (captured < lo) {
cap_load(s, cs);
return NULL;
}
return text;
}
/* Capturing rules */
case RULE_GETTAG: {
uint32_t search = rule[1];
uint32_t tag = rule[2];
for (int32_t i = s->tags->count - 1; i >= 0; i--) {
if (s->tags->data[i] == search) {
pushcap(s, s->tagged_captures->data[i], tag);
return text;
}
}
return NULL;
}
case RULE_POSITION: {
pushcap(s, janet_wrap_number((double)(text - s->text_start)), rule[1]);
return text;
}
case RULE_LINE: {
LineCol lc = get_linecol_from_position(s, (int32_t)(text - s->text_start));
pushcap(s, janet_wrap_number((double)(lc.line)), rule[1]);
return text;
}
case RULE_COLUMN: {
LineCol lc = get_linecol_from_position(s, (int32_t)(text - s->text_start));
pushcap(s, janet_wrap_number((double)(lc.col)), rule[1]);
return text;
}
case RULE_ARGUMENT: {
int32_t index = ((int32_t *)rule)[1];
Janet capture = (index >= s->extrac) ? janet_wrap_nil() : s->extrav[index];
pushcap(s, capture, rule[2]);
return text;
}
case RULE_CONSTANT: {
pushcap(s, s->constants[rule[1]], rule[2]);
return text;
}
case RULE_CAPTURE: {
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
if (!result) return NULL;
/* Specialized pushcap - avoid intermediate string creation */
if (!s->has_backref && s->mode == PEG_MODE_ACCUMULATE) {
janet_buffer_push_bytes(s->scratch, text, (int32_t)(result - text));
} else {
uint32_t tag = rule[2];
pushcap(s, janet_stringv(text, (int32_t)(result - text)), tag);
}
return result;
}
case RULE_CAPTURE_NUM: {
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
if (!result) return NULL;
/* check number parsing */
double x = 0.0;
int32_t base = (int32_t) rule[2];
if (janet_scan_number_base(text, (int32_t)(result - text), base, &x)) return NULL;
/* Specialized pushcap - avoid intermediate string creation */
if (!s->has_backref && s->mode == PEG_MODE_ACCUMULATE) {
janet_buffer_push_bytes(s->scratch, text, (int32_t)(result - text));
} else {
uint32_t tag = rule[3];
pushcap(s, janet_wrap_number(x), tag);
}
return result;
}
case RULE_ACCUMULATE: {
uint32_t tag = rule[2];
int oldmode = s->mode;
if (!tag && oldmode == PEG_MODE_ACCUMULATE) {
rule = s->bytecode + rule[1];
goto tail;
}
CapState cs = cap_save(s);
s->mode = PEG_MODE_ACCUMULATE;
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
s->mode = oldmode;
if (!result) return NULL;
Janet cap = janet_stringv(s->scratch->data + cs.scratch,
s->scratch->count - cs.scratch);
cap_load_keept(s, cs);
pushcap(s, cap, tag);
return result;
}
case RULE_DROP: {
CapState cs = cap_save(s);
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
if (!result) return NULL;
cap_load(s, cs);
return result;
}
case RULE_ONLY_TAGS: {
CapState cs = cap_save(s);
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
if (!result) return NULL;
cap_load_keept(s, cs);
return result;
}
case RULE_GROUP: {
uint32_t tag = rule[2];
int oldmode = s->mode;
CapState cs = cap_save(s);
s->mode = PEG_MODE_NORMAL;
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
s->mode = oldmode;
if (!result) return NULL;
int32_t num_sub_captures = s->captures->count - cs.cap;
JanetArray *sub_captures = janet_array(num_sub_captures);
safe_memcpy(sub_captures->data,
s->captures->data + cs.cap,
sizeof(Janet) * num_sub_captures);
sub_captures->count = num_sub_captures;
cap_load_keept(s, cs);
pushcap(s, janet_wrap_array(sub_captures), tag);
return result;
}
case RULE_NTH: {
uint32_t nth = rule[1];
if (nth > INT32_MAX) nth = INT32_MAX;
uint32_t tag = rule[3];
int oldmode = s->mode;
CapState cs = cap_save(s);
s->mode = PEG_MODE_NORMAL;
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[2], text);
up1(s);
s->mode = oldmode;
if (!result) return NULL;
int32_t num_sub_captures = s->captures->count - cs.cap;
Janet cap;
if (num_sub_captures > (int32_t) nth) {
cap = s->captures->data[cs.cap + nth];
} else {
return NULL;
}
cap_load_keept(s, cs);
pushcap(s, cap, tag);
return result;
}
case RULE_SUB: {
const uint8_t *text_start = text;
const uint32_t *rule_window = s->bytecode + rule[1];
const uint32_t *rule_subpattern = s->bytecode + rule[2];
down1(s);
const uint8_t *window_end = peg_rule(s, rule_window, text);
up1(s);
if (!window_end) {
return NULL;
}
const uint8_t *saved_end = s->text_end;
s->text_end = window_end;
down1(s);
const uint8_t *next_text = peg_rule(s, rule_subpattern, text_start);
up1(s);
s->text_end = saved_end;
if (!next_text) {
return NULL;
}
return window_end;
}
case RULE_SPLIT: {
const uint8_t *saved_end = s->text_end;
const uint32_t *rule_separator = s->bytecode + rule[1];
const uint32_t *rule_subpattern = s->bytecode + rule[2];
const uint8_t *separator_end = NULL;
do {
const uint8_t *text_start = text;
CapState cs = cap_save(s);
down1(s);
while (text <= s->text_end) {
separator_end = peg_rule(s, rule_separator, text);
cap_load(s, cs);
if (separator_end) {
break;
}
text++;
}
up1(s);
if (separator_end) {
s->text_end = text;
text = separator_end;
}
down1(s);
const uint8_t *subpattern_end = peg_rule(s, rule_subpattern, text_start);
up1(s);
s->text_end = saved_end;
if (!subpattern_end) {
return NULL;
}
} while (separator_end);
return s->text_end;
}
case RULE_REPLACE:
case RULE_MATCHTIME: {
uint32_t tag = rule[3];
int oldmode = s->mode;
CapState cs = cap_save(s);
s->mode = PEG_MODE_NORMAL;
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
s->mode = oldmode;
if (!result) return NULL;
Janet cap = janet_wrap_nil();
Janet constant = s->constants[rule[2]];
switch (janet_type(constant)) {
default:
cap = constant;
break;
case JANET_STRUCT:
if (s->captures->count) {
cap = janet_struct_get(janet_unwrap_struct(constant),
s->captures->data[s->captures->count - 1]);
}
break;
case JANET_TABLE:
if (s->captures->count) {
cap = janet_table_get(janet_unwrap_table(constant),
s->captures->data[s->captures->count - 1]);
}
break;
case JANET_CFUNCTION:
cap = janet_unwrap_cfunction(constant)(s->captures->count - cs.cap,
s->captures->data + cs.cap);
break;
case JANET_FUNCTION:
cap = janet_call(janet_unwrap_function(constant),
s->captures->count - cs.cap,
s->captures->data + cs.cap);
break;
}
cap_load_keept(s, cs);
if (rule[0] == RULE_MATCHTIME && !janet_truthy(cap)) return NULL;
pushcap(s, cap, tag);
return result;
}
case RULE_ERROR: {
int oldmode = s->mode;
s->mode = PEG_MODE_NORMAL;
int32_t old_cap = s->captures->count;
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
s->mode = oldmode;
if (!result) return NULL;
if (s->captures->count > old_cap) {
/* Throw last capture */
janet_panicv(s->captures->data[s->captures->count - 1]);
} else {
/* Throw generic error */
int32_t start = (int32_t)(text - s->text_start);
LineCol lc = get_linecol_from_position(s, start);
janet_panicf("match error at line %d, column %d", lc.line, lc.col);
}
return NULL;
}
case RULE_BACKMATCH: {
uint32_t search = rule[1];
for (int32_t i = s->tags->count - 1; i >= 0; i--) {
if (s->tags->data[i] == search) {
Janet capture = s->tagged_captures->data[i];
if (!janet_checktype(capture, JANET_STRING))
return NULL;
const uint8_t *bytes = janet_unwrap_string(capture);
int32_t len = janet_string_length(bytes);
if (text + len > s->text_end)
return NULL;
return memcmp(text, bytes, len) ? NULL : text + len;
}
}
return NULL;
}
case RULE_LENPREFIX: {
int oldmode = s->mode;
s->mode = PEG_MODE_NORMAL;
const uint8_t *next_text;
CapState cs = cap_save(s);
down1(s);
next_text = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
if (NULL == next_text) return NULL;
s->mode = oldmode;
int32_t num_sub_captures = s->captures->count - cs.cap;
Janet lencap;
if (num_sub_captures <= 0 ||
(lencap = s->captures->data[cs.cap], !janet_checkint(lencap))) {
cap_load(s, cs);
return NULL;
}
int32_t nrep = janet_unwrap_integer(lencap);
/* drop captures from len pattern */
cap_load(s, cs);
for (int32_t i = 0; i < nrep; i++) {
down1(s);
next_text = peg_rule(s, s->bytecode + rule[2], next_text);
up1(s);
if (NULL == next_text) {
cap_load(s, cs);
return NULL;
}
}
return next_text;
}
case RULE_READINT: {
uint32_t tag = rule[2];
uint32_t signedness = rule[1] & 0x10;
uint32_t endianness = rule[1] & 0x20;
int width = (int)(rule[1] & 0xF);
if (text + width > s->text_end) return NULL;
uint64_t accum = 0;
if (endianness) {
/* BE */
for (int i = 0; i < width; i++) accum = (accum << 8) | text[i];
} else {
/* LE */
for (int i = width - 1; i >= 0; i--) accum = (accum << 8) | text[i];
}
Janet capture_value;
/* We can only parse integeres of greater than 6 bytes reliable if int-types are enabled.
* Otherwise, we may lose precision, so 6 is the maximum size when int-types are disabled. */
#ifdef JANET_INT_TYPES
if (width > 6) {
if (signedness) {
capture_value = janet_wrap_s64(peg_convert_u64_s64(accum, width));
} else {
capture_value = janet_wrap_u64(accum);
}
} else
#endif
{
double double_value;
if (signedness) {
double_value = (double)(peg_convert_u64_s64(accum, width));
} else {
double_value = (double)accum;
}
capture_value = janet_wrap_number(double_value);
}
pushcap(s, capture_value, tag);
return text + width;
}
case RULE_UNREF: {
int32_t tcap = s->tags->count;
down1(s);
const uint8_t *result = peg_rule(s, s->bytecode + rule[1], text);
up1(s);
if (!result) return NULL;
int32_t final_tcap = s->tags->count;
/* Truncate tagged captures to not include items of the given tag */
int32_t w = tcap;
/* If no tag is given, drop ALL tagged captures */
if (rule[2]) {
for (int32_t i = tcap; i < final_tcap; i++) {
if (s->tags->data[i] != (0xFF & rule[2])) {
s->tags->data[w] = s->tags->data[i];
s->tagged_captures->data[w] = s->tagged_captures->data[i];
w++;
}
}
}
s->tags->count = w;
s->tagged_captures->count = w;
return result;
}
}
}
/*
* Compilation
*/
typedef struct {
JanetTable *grammar;
JanetTable *default_grammar;
JanetTable *tags;
Janet *constants;
uint32_t *bytecode;
Janet form;
int depth;
uint32_t nexttag;
int has_backref;
} Builder;
/* Forward declaration to allow recursion */
static uint32_t peg_compile1(Builder *b, Janet peg);
/*
* Errors
*/
static void builder_cleanup(Builder *b) {
janet_v_free(b->constants);
janet_v_free(b->bytecode);
}
JANET_NO_RETURN static void peg_panic(Builder *b, const char *msg) {
builder_cleanup(b);
janet_panicf("grammar error in %p, %s", b->form, msg);
}
#define peg_panicf(b,...) peg_panic((b), (const char *) janet_formatc(__VA_ARGS__))
static void peg_fixarity(Builder *b, int32_t argc, int32_t arity) {
if (argc != arity) {
peg_panicf(b, "expected %d argument%s, got %d",
arity,
arity == 1 ? "" : "s",
argc);
}
}
static void peg_arity(Builder *b, int32_t arity, int32_t min, int32_t max) {
if (min >= 0 && arity < min)
peg_panicf(b, "arity mismatch, expected at least %d, got %d", min, arity);
if (max >= 0 && arity > max)
peg_panicf(b, "arity mismatch, expected at most %d, got %d", max, arity);
}
static const uint8_t *peg_getset(Builder *b, Janet x) {
if (!janet_checktype(x, JANET_STRING))
peg_panic(b, "expected string for character set");
const uint8_t *str = janet_unwrap_string(x);
return str;
}
static const uint8_t *peg_getrange(Builder *b, Janet x) {
if (!janet_checktype(x, JANET_STRING))
peg_panic(b, "expected string for character range");
const uint8_t *str = janet_unwrap_string(x);
if (janet_string_length(str) != 2)
peg_panicf(b, "expected string to have length 2, got %v", x);
if (str[1] < str[0])
peg_panicf(b, "range %v is empty", x);
return str;
}
static int32_t peg_getinteger(Builder *b, Janet x) {
if (!janet_checkint(x))
peg_panicf(b, "expected integer, got %v", x);
return janet_unwrap_integer(x);
}
static int32_t peg_getnat(Builder *b, Janet x) {
int32_t i = peg_getinteger(b, x);
if (i < 0)
peg_panicf(b, "expected non-negative integer, got %v", x);
return i;
}
/*
* Emission
*/
static uint32_t emit_constant(Builder *b, Janet c) {
uint32_t cindex = (uint32_t) janet_v_count(b->constants);
janet_v_push(b->constants, c);
return cindex;
}
static uint32_t emit_tag(Builder *b, Janet t) {
if (!janet_checktype(t, JANET_KEYWORD))
peg_panicf(b, "expected keyword for capture tag, got %v", t);
Janet check = janet_table_get(b->tags, t);
if (janet_checktype(check, JANET_NIL)) {
uint32_t tag = b->nexttag++;
if (tag > 255) {
peg_panic(b, "too many tags - up to 255 tags are supported per peg");
}
Janet val = janet_wrap_number(tag);
janet_table_put(b->tags, t, val);
return tag;
} else {
return (uint32_t) janet_unwrap_number(check);
}
}
/* Reserve space in bytecode for a rule. When a special emits a rule,
* it must place that rule immediately on the bytecode stack. This lets
* the compiler know where the rule is going to be before it is complete,
* allowing recursive rules. */
typedef struct {
Builder *builder;
uint32_t index;
int32_t size;
} Reserve;
static Reserve reserve(Builder *b, int32_t size) {
Reserve r;
r.index = janet_v_count(b->bytecode);
r.builder = b;
r.size = size;
for (int32_t i = 0; i < size; i++)
janet_v_push(b->bytecode, 0);
return r;
}
/* Emit a rule in the builder. Returns the index of the new rule */
static void emit_rule(Reserve r, int32_t op, int32_t n, const uint32_t *body) {
janet_assert(r.size == n + 1, "bad reserve");
r.builder->bytecode[r.index] = op;
memcpy(r.builder->bytecode + r.index + 1, body, n * sizeof(uint32_t));
}
/* For RULE_LITERAL */
static void emit_bytes(Builder *b, uint32_t op, int32_t len, const uint8_t *bytes) {
uint32_t next_rule = janet_v_count(b->bytecode);
janet_v_push(b->bytecode, op);
janet_v_push(b->bytecode, len);
int32_t words = ((len + 3) >> 2);
for (int32_t i = 0; i < words; i++)
janet_v_push(b->bytecode, 0);
memcpy(b->bytecode + next_rule + 2, bytes, len);
}
/* For fixed arity rules of arities 1, 2, and 3 */
static void emit_1(Reserve r, uint32_t op, uint32_t arg) {
emit_rule(r, op, 1, &arg);
}
static void emit_2(Reserve r, uint32_t op, uint32_t arg1, uint32_t arg2) {
uint32_t arr[2] = {arg1, arg2};
emit_rule(r, op, 2, arr);
}
static void emit_3(Reserve r, uint32_t op, uint32_t arg1, uint32_t arg2, uint32_t arg3) {
uint32_t arr[3] = {arg1, arg2, arg3};
emit_rule(r, op, 3, arr);
}
/*
* Specials
*/
static void bitmap_set(uint32_t *bitmap, uint8_t c) {
bitmap[c >> 5] |= ((uint32_t)1) << (c & 0x1F);
}
static void spec_range(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 1, -1);
if (argc == 1) {
Reserve r = reserve(b, 2);
const uint8_t *str = peg_getrange(b, argv[0]);
uint32_t arg = str[0] | (str[1] << 16);
emit_1(r, RULE_RANGE, arg);
} else {
/* Compile as a set */
Reserve r = reserve(b, 9);
uint32_t bitmap[8] = {0};
for (int32_t i = 0; i < argc; i++) {
const uint8_t *str = peg_getrange(b, argv[i]);
for (uint32_t c = str[0]; c <= str[1]; c++)
bitmap_set(bitmap, c);
}
emit_rule(r, RULE_SET, 8, bitmap);
}
}
static void spec_set(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 1);
Reserve r = reserve(b, 9);
const uint8_t *str = peg_getset(b, argv[0]);
uint32_t bitmap[8] = {0};
for (int32_t i = 0; i < janet_string_length(str); i++)
bitmap_set(bitmap, str[i]);
emit_rule(r, RULE_SET, 8, bitmap);
}
static void spec_look(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 1, 2);
Reserve r = reserve(b, 3);
int32_t rulearg = argc == 2 ? 1 : 0;
int32_t offset = argc == 2 ? peg_getinteger(b, argv[0]) : 0;
uint32_t subrule = peg_compile1(b, argv[rulearg]);
emit_2(r, RULE_LOOK, (uint32_t) offset, subrule);
}
/* Rule of the form [len, rules...] */
static void spec_variadic(Builder *b, int32_t argc, const Janet *argv, uint32_t op) {
uint32_t rule = janet_v_count(b->bytecode);
janet_v_push(b->bytecode, op);
janet_v_push(b->bytecode, argc);
for (int32_t i = 0; i < argc; i++)
janet_v_push(b->bytecode, 0);
for (int32_t i = 0; i < argc; i++) {
uint32_t rulei = peg_compile1(b, argv[i]);
b->bytecode[rule + 2 + i] = rulei;
}
}
static void spec_choice(Builder *b, int32_t argc, const Janet *argv) {
spec_variadic(b, argc, argv, RULE_CHOICE);
}
static void spec_sequence(Builder *b, int32_t argc, const Janet *argv) {
spec_variadic(b, argc, argv, RULE_SEQUENCE);
}
/* For (if a b) and (if-not a b) */
static void spec_branch(Builder *b, int32_t argc, const Janet *argv, uint32_t rule) {
peg_fixarity(b, argc, 2);
Reserve r = reserve(b, 3);
uint32_t rule_a = peg_compile1(b, argv[0]);
uint32_t rule_b = peg_compile1(b, argv[1]);
emit_2(r, rule, rule_a, rule_b);
}
static void spec_if(Builder *b, int32_t argc, const Janet *argv) {
spec_branch(b, argc, argv, RULE_IF);
}
static void spec_ifnot(Builder *b, int32_t argc, const Janet *argv) {
spec_branch(b, argc, argv, RULE_IFNOT);
}
static void spec_lenprefix(Builder *b, int32_t argc, const Janet *argv) {
spec_branch(b, argc, argv, RULE_LENPREFIX);
}
static void spec_between(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 3);
Reserve r = reserve(b, 4);
int32_t lo = peg_getnat(b, argv[0]);
int32_t hi = peg_getnat(b, argv[1]);
uint32_t subrule = peg_compile1(b, argv[2]);
emit_3(r, RULE_BETWEEN, lo, hi, subrule);
}
static void spec_repeater(Builder *b, int32_t argc, const Janet *argv, int32_t min) {
peg_fixarity(b, argc, 1);
Reserve r = reserve(b, 4);
uint32_t subrule = peg_compile1(b, argv[0]);
emit_3(r, RULE_BETWEEN, min, UINT32_MAX, subrule);
}
static void spec_some(Builder *b, int32_t argc, const Janet *argv) {
spec_repeater(b, argc, argv, 1);
}
static void spec_any(Builder *b, int32_t argc, const Janet *argv) {
spec_repeater(b, argc, argv, 0);
}
static void spec_atleast(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 2);
Reserve r = reserve(b, 4);
int32_t n = peg_getnat(b, argv[0]);
uint32_t subrule = peg_compile1(b, argv[1]);
emit_3(r, RULE_BETWEEN, n, UINT32_MAX, subrule);
}
static void spec_atmost(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 2);
Reserve r = reserve(b, 4);
int32_t n = peg_getnat(b, argv[0]);
uint32_t subrule = peg_compile1(b, argv[1]);
emit_3(r, RULE_BETWEEN, 0, n, subrule);
}
static void spec_opt(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 1);
Reserve r = reserve(b, 4);
uint32_t subrule = peg_compile1(b, argv[0]);
emit_3(r, RULE_BETWEEN, 0, 1, subrule);
}
static void spec_repeat(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 2);
Reserve r = reserve(b, 4);
int32_t n = peg_getnat(b, argv[0]);
uint32_t subrule = peg_compile1(b, argv[1]);
emit_3(r, RULE_BETWEEN, n, n, subrule);
}
/* Rule of the form [rule] */
static void spec_onerule(Builder *b, int32_t argc, const Janet *argv, uint32_t op) {
peg_fixarity(b, argc, 1);
Reserve r = reserve(b, 2);
uint32_t rule = peg_compile1(b, argv[0]);
emit_1(r, op, rule);
}
static void spec_not(Builder *b, int32_t argc, const Janet *argv) {
spec_onerule(b, argc, argv, RULE_NOT);
}
static void spec_error(Builder *b, int32_t argc, const Janet *argv) {
if (argc == 0) {
Reserve r = reserve(b, 2);
uint32_t rule = peg_compile1(b, janet_wrap_number(0));
emit_1(r, RULE_ERROR, rule);
} else {
spec_onerule(b, argc, argv, RULE_ERROR);
}
}
static void spec_to(Builder *b, int32_t argc, const Janet *argv) {
spec_onerule(b, argc, argv, RULE_TO);
}
static void spec_thru(Builder *b, int32_t argc, const Janet *argv) {
spec_onerule(b, argc, argv, RULE_THRU);
}
static void spec_drop(Builder *b, int32_t argc, const Janet *argv) {
spec_onerule(b, argc, argv, RULE_DROP);
}
static void spec_only_tags(Builder *b, int32_t argc, const Janet *argv) {
spec_onerule(b, argc, argv, RULE_ONLY_TAGS);
}
/* Rule of the form [rule, tag] */
static void spec_cap1(Builder *b, int32_t argc, const Janet *argv, uint32_t op) {
peg_arity(b, argc, 1, 2);
Reserve r = reserve(b, 3);
uint32_t tag = (argc == 2) ? emit_tag(b, argv[1]) : 0;
uint32_t rule = peg_compile1(b, argv[0]);
emit_2(r, op, rule, tag);
}
static void spec_capture(Builder *b, int32_t argc, const Janet *argv) {
spec_cap1(b, argc, argv, RULE_CAPTURE);
}
static void spec_accumulate(Builder *b, int32_t argc, const Janet *argv) {
spec_cap1(b, argc, argv, RULE_ACCUMULATE);
}
static void spec_group(Builder *b, int32_t argc, const Janet *argv) {
spec_cap1(b, argc, argv, RULE_GROUP);
}
static void spec_unref(Builder *b, int32_t argc, const Janet *argv) {
spec_cap1(b, argc, argv, RULE_UNREF);
}
static void spec_nth(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 2, 3);
Reserve r = reserve(b, 4);
uint32_t nth = peg_getnat(b, argv[0]);
uint32_t rule = peg_compile1(b, argv[1]);
uint32_t tag = (argc == 3) ? emit_tag(b, argv[2]) : 0;
emit_3(r, RULE_NTH, nth, rule, tag);
}
static void spec_capture_number(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 1, 3);
Reserve r = reserve(b, 4);
uint32_t base = 0;
if (argc >= 2) {
if (!janet_checktype(argv[1], JANET_NIL)) {
if (!janet_checkint(argv[1])) goto error;
base = (uint32_t) janet_unwrap_integer(argv[1]);
if (base < 2 || base > 36) goto error;
}
}
uint32_t tag = (argc == 3) ? emit_tag(b, argv[2]) : 0;
uint32_t rule = peg_compile1(b, argv[0]);
emit_3(r, RULE_CAPTURE_NUM, rule, base, tag);
return;
error:
peg_panicf(b, "expected integer between 2 and 36, got %v", argv[1]);
}
static void spec_reference(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 1, 2);
Reserve r = reserve(b, 3);
uint32_t search = emit_tag(b, argv[0]);
uint32_t tag = (argc == 2) ? emit_tag(b, argv[1]) : 0;
b->has_backref = 1;
emit_2(r, RULE_GETTAG, search, tag);
}
static void spec_tag1(Builder *b, int32_t argc, const Janet *argv, uint32_t op) {
peg_arity(b, argc, 0, 1);
Reserve r = reserve(b, 2);
uint32_t tag = (argc) ? emit_tag(b, argv[0]) : 0;
(void) argv;
emit_1(r, op, tag);
}
static void spec_position(Builder *b, int32_t argc, const Janet *argv) {
spec_tag1(b, argc, argv, RULE_POSITION);
}
static void spec_line(Builder *b, int32_t argc, const Janet *argv) {
spec_tag1(b, argc, argv, RULE_LINE);
}
static void spec_column(Builder *b, int32_t argc, const Janet *argv) {
spec_tag1(b, argc, argv, RULE_COLUMN);
}
static void spec_backmatch(Builder *b, int32_t argc, const Janet *argv) {
b->has_backref = 1;
spec_tag1(b, argc, argv, RULE_BACKMATCH);
}
static void spec_argument(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 1, 2);
Reserve r = reserve(b, 3);
uint32_t tag = (argc == 2) ? emit_tag(b, argv[1]) : 0;
int32_t index = peg_getnat(b, argv[0]);
emit_2(r, RULE_ARGUMENT, index, tag);
}
static void spec_constant(Builder *b, int32_t argc, const Janet *argv) {
janet_arity(argc, 1, 2);
Reserve r = reserve(b, 3);
uint32_t tag = (argc == 2) ? emit_tag(b, argv[1]) : 0;
emit_2(r, RULE_CONSTANT, emit_constant(b, argv[0]), tag);
}
static void spec_replace(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 2, 3);
Reserve r = reserve(b, 4);
uint32_t subrule = peg_compile1(b, argv[0]);
uint32_t constant = emit_constant(b, argv[1]);
uint32_t tag = (argc == 3) ? emit_tag(b, argv[2]) : 0;
emit_3(r, RULE_REPLACE, subrule, constant, tag);
}
static void spec_matchtime(Builder *b, int32_t argc, const Janet *argv) {
peg_arity(b, argc, 2, 3);
Reserve r = reserve(b, 4);
uint32_t subrule = peg_compile1(b, argv[0]);
Janet fun = argv[1];
if (!janet_checktype(fun, JANET_FUNCTION) &&
!janet_checktype(fun, JANET_CFUNCTION)) {
peg_panicf(b, "expected function or cfunction, got %v", fun);
}
uint32_t tag = (argc == 3) ? emit_tag(b, argv[2]) : 0;
uint32_t cindex = emit_constant(b, fun);
emit_3(r, RULE_MATCHTIME, subrule, cindex, tag);
}
static void spec_sub(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 2);
Reserve r = reserve(b, 3);
uint32_t subrule1 = peg_compile1(b, argv[0]);
uint32_t subrule2 = peg_compile1(b, argv[1]);
emit_2(r, RULE_SUB, subrule1, subrule2);
}
static void spec_split(Builder *b, int32_t argc, const Janet *argv) {
peg_fixarity(b, argc, 2);
Reserve r = reserve(b, 3);
uint32_t subrule1 = peg_compile1(b, argv[0]);
uint32_t subrule2 = peg_compile1(b, argv[1]);
emit_2(r, RULE_SPLIT, subrule1, subrule2);
}
#ifdef JANET_INT_TYPES
#define JANET_MAX_READINT_WIDTH 8
#else
#define JANET_MAX_READINT_WIDTH 6
#endif
static void spec_readint(Builder *b, int32_t argc, const Janet *argv, uint32_t mask) {
peg_arity(b, argc, 1, 2);
Reserve r = reserve(b, 3);
uint32_t tag = (argc == 2) ? emit_tag(b, argv[1]) : 0;
int32_t width = peg_getnat(b, argv[0]);
if ((width < 0) || (width > JANET_MAX_READINT_WIDTH)) {
peg_panicf(b, "width must be between 0 and %d, got %d", JANET_MAX_READINT_WIDTH, width);
}
emit_2(r, RULE_READINT, mask | ((uint32_t) width), tag);
}
static void spec_uint_le(Builder *b, int32_t argc, const Janet *argv) {
spec_readint(b, argc, argv, 0x0u);
}
static void spec_int_le(Builder *b, int32_t argc, const Janet *argv) {
spec_readint(b, argc, argv, 0x10u);
}
static void spec_uint_be(Builder *b, int32_t argc, const Janet *argv) {
spec_readint(b, argc, argv, 0x20u);
}
static void spec_int_be(Builder *b, int32_t argc, const Janet *argv) {
spec_readint(b, argc, argv, 0x30u);
}
/* Special compiler form */
typedef void (*Special)(Builder *b, int32_t argc, const Janet *argv);
typedef struct {
const char *name;
Special special;
} SpecialPair;
/* Keep in lexical order (vim :sort works well) */
static const SpecialPair peg_specials[] = {
{"!", spec_not},
{"$", spec_position},
{"%", spec_accumulate},
{"*", spec_sequence},
{"+", spec_choice},
{"->", spec_reference},
{"/", spec_replace},
{"<-", spec_capture},
{">", spec_look},
{"?", spec_opt},
{"accumulate", spec_accumulate},
{"any", spec_any},
{"argument", spec_argument},
{"at-least", spec_atleast},
{"at-most", spec_atmost},
{"backmatch", spec_backmatch},
{"backref", spec_reference},
{"between", spec_between},
{"capture", spec_capture},
{"choice", spec_choice},
{"cmt", spec_matchtime},
{"column", spec_column},
{"constant", spec_constant},
{"drop", spec_drop},
{"error", spec_error},
{"group", spec_group},
{"if", spec_if},
{"if-not", spec_ifnot},
{"int", spec_int_le},
{"int-be", spec_int_be},
{"lenprefix", spec_lenprefix},
{"line", spec_line},
{"look", spec_look},
{"not", spec_not},
{"nth", spec_nth},
{"number", spec_capture_number},
{"only-tags", spec_only_tags},
{"opt", spec_opt},
{"position", spec_position},
{"quote", spec_capture},
{"range", spec_range},
{"repeat", spec_repeat},
{"replace", spec_replace},
{"sequence", spec_sequence},
{"set", spec_set},
{"some", spec_some},
{"split", spec_split},
{"sub", spec_sub},
{"thru", spec_thru},
{"to", spec_to},
{"uint", spec_uint_le},
{"uint-be", spec_uint_be},
{"unref", spec_unref},
};
/* Compile a janet value into a rule and return the rule index. */
static uint32_t peg_compile1(Builder *b, Janet peg) {
/* Keep track of the form being compiled for error purposes */
Janet old_form = b->form;
JanetTable *old_grammar = b->grammar;
b->form = peg;
/* Resolve keyword references */
int i = JANET_RECURSION_GUARD;
JanetTable *grammar = old_grammar;
for (; i > 0 && janet_checktype(peg, JANET_KEYWORD); --i) {
Janet nextPeg = janet_table_get_ex(grammar, peg, &grammar);
if (!grammar || janet_checktype(nextPeg, JANET_NIL)) {
nextPeg = (b->default_grammar == NULL)
? janet_wrap_nil()
: janet_table_get(b->default_grammar, peg);
if (janet_checktype(nextPeg, JANET_NIL)) {
peg_panic(b, "unknown rule");
}
}
peg = nextPeg;
b->form = peg;
b->grammar = grammar;
}
if (i == 0)
peg_panic(b, "reference chain too deep");
/* Check cache - for tuples we check only the local cache, as
* in a different grammar, the same tuple can compile to a different
* rule - for example, (+ :a :b) depends on whatever :a and :b are bound to. */
Janet check = janet_checktype(peg, JANET_TUPLE)
? janet_table_rawget(grammar, peg)
: janet_table_get(grammar, peg);
if (!janet_checktype(check, JANET_NIL)) {
b->form = old_form;
b->grammar = old_grammar;
return (uint32_t) janet_unwrap_number(check);
}
/* Check depth */
if (b->depth-- == 0)
peg_panic(b, "peg grammar recursed too deeply");
/* The final rule to return */
uint32_t rule = janet_v_count(b->bytecode);
/* Add to cache. Do not cache structs, as we don't yet know
* what rule they will return! We can just as effectively cache
* the structs main rule. */
if (!janet_checktype(peg, JANET_STRUCT)) {
JanetTable *which_grammar = grammar;
/* If we are a primitive pattern, add to the global cache (root grammar table) */
if (!janet_checktype(peg, JANET_TUPLE)) {
while (which_grammar->proto)
which_grammar = which_grammar->proto;
}
janet_table_put(which_grammar, peg, janet_wrap_number(rule));
}
switch (janet_type(peg)) {
default:
peg_panic(b, "unexpected peg source");
return 0;
case JANET_BOOLEAN: {
int n = janet_unwrap_boolean(peg);
Reserve r = reserve(b, 2);
emit_1(r, n ? RULE_NCHAR : RULE_NOTNCHAR, 0);
break;
}
case JANET_NUMBER: {
int32_t n = peg_getinteger(b, peg);
Reserve r = reserve(b, 2);
if (n < 0) {
emit_1(r, RULE_NOTNCHAR, -n);
} else {
emit_1(r, RULE_NCHAR, n);
}
break;
}
case JANET_STRING: {
const uint8_t *str = janet_unwrap_string(peg);
int32_t len = janet_string_length(str);
emit_bytes(b, RULE_LITERAL, len, str);
break;
}
case JANET_TABLE: {
/* Build grammar table */
JanetTable *new_grammar = janet_table_clone(janet_unwrap_table(peg));
new_grammar->proto = grammar;
b->grammar = grammar = new_grammar;
/* Run the main rule */
Janet main_rule = janet_table_rawget(grammar, janet_ckeywordv("main"));
if (janet_checktype(main_rule, JANET_NIL))
peg_panic(b, "grammar requires :main rule");
rule = peg_compile1(b, main_rule);
break;
}
case JANET_STRUCT: {
/* Build grammar table */
const JanetKV *st = janet_unwrap_struct(peg);
JanetTable *new_grammar = janet_table(2 * janet_struct_capacity(st));
for (int32_t i = 0; i < janet_struct_capacity(st); i++) {
if (janet_checktype(st[i].key, JANET_KEYWORD)) {
janet_table_put(new_grammar, st[i].key, st[i].value);
}
}
new_grammar->proto = grammar;
b->grammar = grammar = new_grammar;
/* Run the main rule */
Janet main_rule = janet_table_rawget(grammar, janet_ckeywordv("main"));
if (janet_checktype(main_rule, JANET_NIL))
peg_panic(b, "grammar requires :main rule");
rule = peg_compile1(b, main_rule);
break;
}
case JANET_TUPLE: {
const Janet *tup = janet_unwrap_tuple(peg);
int32_t len = janet_tuple_length(tup);
if (len == 0) peg_panic(b, "tuple in grammar must have non-zero length");
if (janet_checkint(tup[0])) {
int32_t n = janet_unwrap_integer(tup[0]);
if (n < 0) {
peg_panicf(b, "expected non-negative integer, got %d", n);
}
spec_repeat(b, len, tup);
break;
}
if (!janet_checktype(tup[0], JANET_SYMBOL))
peg_panicf(b, "expected grammar command, found %v", tup[0]);
const uint8_t *sym = janet_unwrap_symbol(tup[0]);
const SpecialPair *sp = janet_strbinsearch(
&peg_specials,
sizeof(peg_specials) / sizeof(SpecialPair),
sizeof(SpecialPair),
sym);
if (sp) {
sp->special(b, len - 1, tup + 1);
} else {
peg_panicf(b, "unknown special %S", sym);
}
break;
}
}
/* Increase depth again */
b->depth++;
b->form = old_form;
b->grammar = old_grammar;
return rule;
}
/*
* Post-Compilation
*/
static int peg_mark(void *p, size_t size) {
(void) size;
JanetPeg *peg = (JanetPeg *)p;
if (NULL != peg->constants)
for (uint32_t i = 0; i < peg->num_constants; i++)
janet_mark(peg->constants[i]);
return 0;
}
static void peg_marshal(void *p, JanetMarshalContext *ctx) {
JanetPeg *peg = (JanetPeg *)p;
janet_marshal_size(ctx, peg->bytecode_len);
janet_marshal_int(ctx, (int32_t)peg->num_constants);
janet_marshal_abstract(ctx, p);
for (size_t i = 0; i < peg->bytecode_len; i++)
janet_marshal_int(ctx, (int32_t) peg->bytecode[i]);
for (uint32_t j = 0; j < peg->num_constants; j++)
janet_marshal_janet(ctx, peg->constants[j]);
}
/* Used to ensure that if we place several arrays in one memory chunk, each
* array will be correctly aligned */
static size_t size_padded(size_t offset, size_t size) {
size_t x = size + offset - 1;
return x - (x % size);
}
static void *peg_unmarshal(JanetMarshalContext *ctx) {
size_t bytecode_len = janet_unmarshal_size(ctx);
uint32_t num_constants = (uint32_t) janet_unmarshal_int(ctx);
/* Calculate offsets. Should match those in make_peg */
size_t bytecode_start = size_padded(sizeof(JanetPeg), sizeof(uint32_t));
size_t bytecode_size = bytecode_len * sizeof(uint32_t);
size_t constants_start = size_padded(bytecode_start + bytecode_size, sizeof(Janet));
size_t total_size = constants_start + sizeof(Janet) * (size_t) num_constants;
/* DOS prevention? I.E. we could read bytecode and constants before
* hand so we don't allocated a ton of memory on bad, short input */
/* Allocate PEG */
char *mem = janet_unmarshal_abstract(ctx, total_size);
JanetPeg *peg = (JanetPeg *)mem;
uint32_t *bytecode = (uint32_t *)(mem + bytecode_start);
Janet *constants = (Janet *)(mem + constants_start);
peg->bytecode = NULL;
peg->constants = NULL;
peg->bytecode_len = bytecode_len;
peg->num_constants = num_constants;
for (size_t i = 0; i < peg->bytecode_len; i++)
bytecode[i] = (uint32_t) janet_unmarshal_int(ctx);
for (uint32_t j = 0; j < peg->num_constants; j++)
constants[j] = janet_unmarshal_janet(ctx);
/* After here, no panics except for the bad: label. */
/* Keep track at each index if an instruction was
* reference (0x01) or is in a main bytecode position
* (0x02). This lets us do a linear scan and not
* need to a depth first traversal. It is stricter
* than a dfs by not allowing certain kinds of unused
* bytecode. */
uint32_t blen = (int32_t) peg->bytecode_len;
uint32_t clen = peg->num_constants;
uint8_t *op_flags = janet_calloc(1, blen);
if (NULL == op_flags) {
JANET_OUT_OF_MEMORY;
}
/* verify peg bytecode */
int32_t has_backref = 0;
uint32_t i = 0;
while (i < blen) {
uint32_t instr = bytecode[i];
uint32_t *rule = bytecode + i;
op_flags[i] |= 0x02;
switch (instr) {
case RULE_LITERAL:
i += 2 + ((rule[1] + 3) >> 2);
break;
case RULE_NCHAR:
case RULE_NOTNCHAR:
case RULE_RANGE:
case RULE_POSITION:
case RULE_LINE:
case RULE_COLUMN:
/* [1 word] */
i += 2;
break;
case RULE_BACKMATCH:
/* [1 word] */
i += 2;
has_backref = 1;
break;
case RULE_SET:
/* [8 words] */
i += 9;
break;
case RULE_LOOK:
/* [offset, rule] */
if (rule[2] >= blen) goto bad;
op_flags[rule[2]] |= 0x1;
i += 3;
break;
case RULE_CHOICE:
case RULE_SEQUENCE:
/* [len, rules...] */
{
uint32_t len = rule[1];
for (uint32_t j = 0; j < len; j++) {
if (rule[2 + j] >= blen) goto bad;
op_flags[rule[2 + j]] |= 0x1;
}
i += 2 + len;
}
break;
case RULE_IF:
case RULE_IFNOT:
case RULE_LENPREFIX:
/* [rule_a, rule_b (b if not a)] */
if (rule[1] >= blen) goto bad;
if (rule[2] >= blen) goto bad;
op_flags[rule[1]] |= 0x01;
op_flags[rule[2]] |= 0x01;
i += 3;
break;
case RULE_BETWEEN:
/* [lo, hi, rule] */
if (rule[3] >= blen) goto bad;
op_flags[rule[3]] |= 0x01;
i += 4;
break;
case RULE_ARGUMENT:
/* [searchtag, tag] */
i += 3;
break;
case RULE_GETTAG:
/* [searchtag, tag] */
i += 3;
has_backref = 1;
break;
case RULE_CONSTANT:
/* [constant, tag] */
if (rule[1] >= clen) goto bad;
i += 3;
break;
case RULE_CAPTURE_NUM:
/* [rule, base, tag] */
if (rule[1] >= blen) goto bad;
op_flags[rule[1]] |= 0x01;
i += 4;
break;
case RULE_ACCUMULATE:
case RULE_GROUP:
case RULE_CAPTURE:
case RULE_UNREF:
/* [rule, tag] */
if (rule[1] >= blen) goto bad;
op_flags[rule[1]] |= 0x01;
i += 3;
break;
case RULE_REPLACE:
case RULE_MATCHTIME:
/* [rule, constant, tag] */
if (rule[1] >= blen) goto bad;
if (rule[2] >= clen) goto bad;
op_flags[rule[1]] |= 0x01;
i += 4;
break;
case RULE_SUB:
case RULE_SPLIT:
/* [rule, rule] */
if (rule[1] >= blen) goto bad;
if (rule[2] >= blen) goto bad;
op_flags[rule[1]] |= 0x01;
op_flags[rule[2]] |= 0x01;
i += 3;
break;
case RULE_ERROR:
case RULE_DROP:
case RULE_ONLY_TAGS:
case RULE_NOT:
case RULE_TO:
case RULE_THRU:
/* [rule] */
if (rule[1] >= blen) goto bad;
op_flags[rule[1]] |= 0x01;
i += 2;
break;
case RULE_READINT:
/* [ width | (endianness << 5) | (signedness << 6), tag ] */
if (rule[1] > JANET_MAX_READINT_WIDTH) goto bad;
i += 3;
break;
case RULE_NTH:
/* [nth, rule, tag] */
if (rule[2] >= blen) goto bad;
op_flags[rule[2]] |= 0x01;
i += 4;
break;
default:
goto bad;
}
}
/* last instruction cannot overflow */
if (i != blen) goto bad;
/* Make sure all referenced instructions are actually
* in instruction positions. */
for (i = 0; i < blen; i++)
if (op_flags[i] == 0x01) goto bad;
/* Good return */
peg->bytecode = bytecode;
peg->constants = constants;
peg->has_backref = has_backref;
janet_free(op_flags);
return peg;
bad:
janet_free(op_flags);
janet_panic("invalid peg bytecode");
}
static int cfun_peg_getter(JanetAbstract a, Janet key, Janet *out);
static Janet peg_next(void *p, Janet key);
const JanetAbstractType janet_peg_type = {
"core/peg",
NULL,
peg_mark,
cfun_peg_getter,
NULL, /* put */
peg_marshal,
peg_unmarshal,
NULL, /* tostring */
NULL, /* compare */
NULL, /* hash */
peg_next,
JANET_ATEND_NEXT
};
/* Convert Builder to JanetPeg (Janet Abstract Value) */
static JanetPeg *make_peg(Builder *b) {
size_t bytecode_start = size_padded(sizeof(JanetPeg), sizeof(uint32_t));
size_t bytecode_size = janet_v_count(b->bytecode) * sizeof(uint32_t);
size_t constants_start = size_padded(bytecode_start + bytecode_size, sizeof(Janet));
size_t constants_size = janet_v_count(b->constants) * sizeof(Janet);
size_t total_size = constants_start + constants_size;
char *mem = janet_abstract(&janet_peg_type, total_size);
JanetPeg *peg = (JanetPeg *)mem;
peg->bytecode = (uint32_t *)(mem + bytecode_start);
peg->constants = (Janet *)(mem + constants_start);
peg->num_constants = janet_v_count(b->constants);
safe_memcpy(peg->bytecode, b->bytecode, bytecode_size);
safe_memcpy(peg->constants, b->constants, constants_size);
peg->bytecode_len = janet_v_count(b->bytecode);
peg->has_backref = b->has_backref;
return peg;
}
/* Compiler entry point */
static JanetPeg *compile_peg(Janet x) {
Builder builder;
builder.grammar = janet_table(0);
builder.default_grammar = NULL;
{
Janet default_grammarv = janet_dyn("peg-grammar");
if (janet_checktype(default_grammarv, JANET_TABLE)) {
builder.default_grammar = janet_unwrap_table(default_grammarv);
}
}
builder.tags = janet_table(0);
builder.constants = NULL;
builder.bytecode = NULL;
builder.nexttag = 1;
builder.form = x;
builder.depth = JANET_RECURSION_GUARD;
builder.has_backref = 0;
peg_compile1(&builder, x);
JanetPeg *peg = make_peg(&builder);
builder_cleanup(&builder);
return peg;
}
/*
* C Functions
*/
JANET_CORE_FN(cfun_peg_compile,
"(peg/compile peg)",
"Compiles a peg source data structure into a <core/peg>. This will speed up matching "
"if the same peg will be used multiple times. Will also use `(dyn :peg-grammar)` to supplement "
"the grammar of the peg for otherwise undefined peg keywords.") {
janet_fixarity(argc, 1);
JanetPeg *peg = compile_peg(argv[0]);
return janet_wrap_abstract(peg);
}
/* Common data for peg cfunctions */
typedef struct {
JanetPeg *peg;
PegState s;
JanetByteView bytes;
Janet subst;
int32_t start;
} PegCall;
/* Initialize state for peg cfunctions */
static PegCall peg_cfun_init(int32_t argc, Janet *argv, int get_replace) {
PegCall ret;
int32_t min = get_replace ? 3 : 2;
janet_arity(argc, min, -1);
if (janet_checktype(argv[0], JANET_ABSTRACT) &&
janet_abstract_type(janet_unwrap_abstract(argv[0])) == &janet_peg_type) {
ret.peg = janet_unwrap_abstract(argv[0]);
} else {
ret.peg = compile_peg(argv[0]);
}
if (get_replace) {
ret.subst = argv[1];
ret.bytes = janet_getbytes(argv, 2);
} else {
ret.bytes = janet_getbytes(argv, 1);
}
if (argc > min) {
ret.start = janet_gethalfrange(argv, min, ret.bytes.len, "offset");
ret.s.extrac = argc - min - 1;
ret.s.extrav = janet_tuple_n(argv + min + 1, argc - min - 1);
} else {
ret.start = 0;
ret.s.extrac = 0;
ret.s.extrav = NULL;
}
ret.s.mode = PEG_MODE_NORMAL;
ret.s.text_start = ret.bytes.bytes;
ret.s.text_end = ret.bytes.bytes + ret.bytes.len;
ret.s.outer_text_end = ret.s.text_end;
ret.s.depth = JANET_RECURSION_GUARD;
ret.s.captures = janet_array(0);
ret.s.tagged_captures = janet_array(0);
ret.s.scratch = janet_buffer(10);
ret.s.tags = janet_buffer(10);
ret.s.constants = ret.peg->constants;
ret.s.bytecode = ret.peg->bytecode;
ret.s.linemap = NULL;
ret.s.linemaplen = -1;
ret.s.has_backref = ret.peg->has_backref;
return ret;
}
static void peg_call_reset(PegCall *c) {
c->s.depth = JANET_RECURSION_GUARD;
c->s.captures->count = 0;
c->s.tagged_captures->count = 0;
c->s.scratch->count = 0;
c->s.tags->count = 0;
}
JANET_CORE_FN(cfun_peg_match,
"(peg/match peg text &opt start & args)",
"Match a Parsing Expression Grammar to a byte string and return an array of captured values. "
"Returns nil if text does not match the language defined by peg. The syntax of PEGs is documented on the Janet website.") {
PegCall c = peg_cfun_init(argc, argv, 0);
const uint8_t *result = peg_rule(&c.s, c.s.bytecode, c.bytes.bytes + c.start);
return result ? janet_wrap_array(c.s.captures) : janet_wrap_nil();
}
JANET_CORE_FN(cfun_peg_find,
"(peg/find peg text &opt start & args)",
"Find first index where the peg matches in text. Returns an integer, or nil if not found.") {
PegCall c = peg_cfun_init(argc, argv, 0);
for (int32_t i = c.start; i < c.bytes.len; i++) {
peg_call_reset(&c);
if (peg_rule(&c.s, c.s.bytecode, c.bytes.bytes + i))
return janet_wrap_integer(i);
}
return janet_wrap_nil();
}
JANET_CORE_FN(cfun_peg_find_all,
"(peg/find-all peg text &opt start & args)",
"Find all indexes where the peg matches in text. Returns an array of integers.") {
PegCall c = peg_cfun_init(argc, argv, 0);
JanetArray *ret = janet_array(0);
for (int32_t i = c.start; i < c.bytes.len; i++) {
peg_call_reset(&c);
if (peg_rule(&c.s, c.s.bytecode, c.bytes.bytes + i))
janet_array_push(ret, janet_wrap_integer(i));
}
return janet_wrap_array(ret);
}
static Janet cfun_peg_replace_generic(int32_t argc, Janet *argv, int only_one) {
PegCall c = peg_cfun_init(argc, argv, 1);
JanetBuffer *ret = janet_buffer(0);
int32_t trail = 0;
for (int32_t i = c.start; i < c.bytes.len;) {
peg_call_reset(&c);
const uint8_t *result = peg_rule(&c.s, c.s.bytecode, c.bytes.bytes + i);
if (NULL != result) {
if (trail < i) {
janet_buffer_push_bytes(ret, c.bytes.bytes + trail, (i - trail));
trail = i;
}
int32_t nexti = (int32_t)(result - c.bytes.bytes);
JanetByteView subst = janet_text_substitution(&c.subst, c.bytes.bytes + i, nexti - i, c.s.captures);
janet_buffer_push_bytes(ret, subst.bytes, subst.len);
trail = nexti;
if (nexti == i) nexti++;
i = nexti;
if (only_one) break;
} else {
i++;
}
}
if (trail < c.bytes.len) {
janet_buffer_push_bytes(ret, c.bytes.bytes + trail, (c.bytes.len - trail));
}
return janet_wrap_buffer(ret);
}
JANET_CORE_FN(cfun_peg_replace_all,
"(peg/replace-all peg subst text &opt start & args)",
"Replace all matches of `peg` in `text` with `subst`, returning a new buffer. "
"The peg does not need to make captures to do replacement. "
"If `subst` is a function, it will be called with the "
"matching text followed by any captures.") {
return cfun_peg_replace_generic(argc, argv, 0);
}
JANET_CORE_FN(cfun_peg_replace,
"(peg/replace peg subst text &opt start & args)",
"Replace first match of `peg` in `text` with `subst`, returning a new buffer. "
"The peg does not need to make captures to do replacement. "
"If `subst` is a function, it will be called with the "
"matching text followed by any captures. "
"If no matches are found, returns the input string in a new buffer.") {
return cfun_peg_replace_generic(argc, argv, 1);
}
static JanetMethod peg_methods[] = {
{"match", cfun_peg_match},
{"find", cfun_peg_find},
{"find-all", cfun_peg_find_all},
{"replace", cfun_peg_replace},
{"replace-all", cfun_peg_replace_all},
{NULL, NULL}
};
static int cfun_peg_getter(JanetAbstract a, Janet key, Janet *out) {
(void) a;
if (!janet_checktype(key, JANET_KEYWORD))
return 0;
return janet_getmethod(janet_unwrap_keyword(key), peg_methods, out);
}
static Janet peg_next(void *p, Janet key) {
(void) p;
return janet_nextmethod(peg_methods, key);
}
/* Load the peg module */
void janet_lib_peg(JanetTable *env) {
JanetRegExt cfuns[] = {
JANET_CORE_REG("peg/compile", cfun_peg_compile),
JANET_CORE_REG("peg/match", cfun_peg_match),
JANET_CORE_REG("peg/find", cfun_peg_find),
JANET_CORE_REG("peg/find-all", cfun_peg_find_all),
JANET_CORE_REG("peg/replace", cfun_peg_replace),
JANET_CORE_REG("peg/replace-all", cfun_peg_replace_all),
JANET_REG_END
};
janet_core_cfuns_ext(env, NULL, cfuns);
janet_register_abstract_type(&janet_peg_type);
}
#endif /* ifdef JANET_PEG */
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