911 lines
26 KiB
PHP
911 lines
26 KiB
PHP
|
<?php
|
||
|
|
/*
|
||
|
|
* This program is free software; you can redistribute it and/or modify
|
||
|
|
* it under the terms of the GNU General Public License as published by
|
||
|
|
* the Free Software Foundation; either version 2 of the License, or
|
||
|
|
* (at your option) any later version.
|
||
|
|
*
|
||
|
|
* This program is distributed in the hope that it will be useful,
|
||
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
* GNU Library General Public License for more details.
|
||
|
|
*
|
||
|
|
* You should have received a copy of the GNU General Public License
|
||
|
|
* along with this program; if not, write to the Free Software
|
||
|
|
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
||
|
|
*/
|
||
|
|
|
||
|
|
define('LIME_DIR', dirname(__FILE__));
|
||
|
|
|
||
|
|
function emit($str) { fputs(STDERR, $str."\n"); }
|
||
|
|
|
||
|
|
class Bug extends Exception {}
|
||
|
|
function bug($gripe='Bug found.') { throw new Bug($gripe); }
|
||
|
|
function bug_if($falacy, $gripe='Bug found.') { if ($falacy) throw new Bug($gripe); }
|
||
|
|
function bug_unless($assertion, $gripe='Bug found.') { if (!$assertion) throw new Bug($gripe); }
|
||
|
|
|
||
|
|
include_once(LIME_DIR.'/parse_engine.php');
|
||
|
|
include_once(LIME_DIR.'/set.so.php');
|
||
|
|
include_once(LIME_DIR.'/flex_token_stream.php');
|
||
|
|
|
||
|
|
function lime_token_reference($pos) { return '$tokens['.$pos.']'; }
|
||
|
|
function lime_token_reference_callback($foo) { return lime_token_reference($foo[1]-1); }
|
||
|
|
|
||
|
|
class cf_action {
|
||
|
|
function __construct($code) { $this->code=$code; }
|
||
|
|
}
|
||
|
|
class step {
|
||
|
|
/*
|
||
|
|
Base class for parse table instructions. The main idea is to make the
|
||
|
|
subclasses responsible for conflict resolution among themselves. It also
|
||
|
|
forms a sort of interface to the parse table.
|
||
|
|
*/
|
||
|
|
function __construct($sym) {
|
||
|
|
bug_unless($sym instanceof sym);
|
||
|
|
$this->sym = $sym;
|
||
|
|
}
|
||
|
|
function glyph() { return $this->sym->name; }
|
||
|
|
}
|
||
|
|
class error extends step {
|
||
|
|
function sane() { return false; }
|
||
|
|
function instruction() { bug("This should not happen."); }
|
||
|
|
function decide($that) { return $this; /* An error shall remain one. */ }
|
||
|
|
}
|
||
|
|
class shift extends step {
|
||
|
|
function __construct($sym, $q) {
|
||
|
|
parent::__construct($sym);
|
||
|
|
$this->q = $q;
|
||
|
|
}
|
||
|
|
function sane() { return true; }
|
||
|
|
function instruction() { return "s $this->q"; }
|
||
|
|
function decide($that) {
|
||
|
|
# shift-shift conflicts are impossible.
|
||
|
|
# shift-accept conflicts are a bug.
|
||
|
|
# so we can infer:
|
||
|
|
bug_unless($that instanceof reduce);
|
||
|
|
|
||
|
|
# That being said, the resolution is a matter of precedence.
|
||
|
|
$shift_prec = $this->sym->right_prec;
|
||
|
|
$reduce_prec = $that->rule->prec;
|
||
|
|
|
||
|
|
# If we don't have defined precedence levels for both options,
|
||
|
|
# then we default to shifting:
|
||
|
|
if (!($shift_prec and $reduce_prec)) return $this;
|
||
|
|
|
||
|
|
# Otherwise, use the step with higher precedence.
|
||
|
|
if ($shift_prec > $reduce_prec) return $this;
|
||
|
|
if ($reduce_prec > $shift_prec) return $that;
|
||
|
|
|
||
|
|
# The "nonassoc" works by giving equal precedence to both options,
|
||
|
|
# which means to put an error instruction in the parse table.
|
||
|
|
return new error($this->sym);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class reduce extends step {
|
||
|
|
function __construct($sym, $rule) {
|
||
|
|
bug_unless($rule instanceof rule);
|
||
|
|
parent::__construct($sym);
|
||
|
|
$this->rule = $rule;
|
||
|
|
}
|
||
|
|
function sane() { return true; }
|
||
|
|
function instruction() { return 'r '.$this->rule->id; }
|
||
|
|
function decide($that) {
|
||
|
|
# This means that the input grammar has a reduce-reduce conflict.
|
||
|
|
# Such things are considered an error in the input.
|
||
|
|
throw new RRC($this, $that);
|
||
|
|
#exit(1);
|
||
|
|
# BISON would go with the first encountered reduce thus:
|
||
|
|
# return $this;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class accept extends step {
|
||
|
|
function __construct($sym) { parent::__construct($sym); }
|
||
|
|
function sane() { return true; }
|
||
|
|
function instruction() { return 'a '.$this->sym->name; }
|
||
|
|
}
|
||
|
|
class RRC extends Exception {
|
||
|
|
function __construct($a, $b) {
|
||
|
|
parent::__construct("Reduce-Reduce Conflict");
|
||
|
|
$this->a = $a;
|
||
|
|
$this->b = $b;
|
||
|
|
}
|
||
|
|
function make_noise() {
|
||
|
|
emit(sprintf(
|
||
|
|
"Reduce-Reduce Conflict:\n%s\n%s\nLookahead is (%s)",
|
||
|
|
$this->a->rule->text(),
|
||
|
|
$this->b->rule->text(),
|
||
|
|
$this->a->glyph()
|
||
|
|
));
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class state {
|
||
|
|
function __construct($id, $key, $close) {
|
||
|
|
$this->id = $id;
|
||
|
|
$this->key = $key;
|
||
|
|
$this->close = $close; # config key -> object
|
||
|
|
ksort($this->close);
|
||
|
|
$this->action = array();
|
||
|
|
}
|
||
|
|
function dump() {
|
||
|
|
echo " * ".$this->id.' / '.$this->key."\n";
|
||
|
|
foreach ($this->close as $config) $config->dump();
|
||
|
|
}
|
||
|
|
function add_shift($sym, $state) {
|
||
|
|
$this->add_instruction(new shift($sym, $state->id));
|
||
|
|
}
|
||
|
|
function add_reduce($sym, $rule) {
|
||
|
|
$this->add_instruction(new reduce($sym, $rule));
|
||
|
|
}
|
||
|
|
function add_accept($sym) {
|
||
|
|
$this->add_instruction(new accept($sym));
|
||
|
|
}
|
||
|
|
function add_instruction($step) {
|
||
|
|
bug_unless($step instanceof step);
|
||
|
|
$this->action[] = $step;
|
||
|
|
}
|
||
|
|
function find_reductions($lime) {
|
||
|
|
# rightmost configurations followset yields reduce.
|
||
|
|
foreach($this->close as $c) {
|
||
|
|
if ($c->rightmost) {
|
||
|
|
foreach ($c->follow->all() as $glyph) $this->add_reduce($lime->sym($glyph), $c->rule);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
function resolve_conflicts() {
|
||
|
|
# For each possible lookahead, find one (and only one) step to take.
|
||
|
|
$table = array();
|
||
|
|
foreach ($this->action as $step) {
|
||
|
|
$glyph = $step->glyph();
|
||
|
|
if (isset($table[$glyph])) {
|
||
|
|
# There's a conflict. The shifts all came first, which
|
||
|
|
# simplifies the coding for the step->decide() methods.
|
||
|
|
try {
|
||
|
|
$table[$glyph] = $table[$glyph]->decide($step);
|
||
|
|
} catch (RRC $e) {
|
||
|
|
emit("State $this->id:");
|
||
|
|
$e->make_noise();
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
# This glyph is yet unprocessed, so the step at hand is
|
||
|
|
# our best current guess at what the grammar indicates.
|
||
|
|
$table[$glyph] = $step;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
# Now that we have the correct steps chosen, this routine is oddly
|
||
|
|
# also responsible for turning that table into the form that will
|
||
|
|
# eventually be passed to the parse engine. (So FIXME?)
|
||
|
|
$out = array();
|
||
|
|
foreach ($table as $glyph => $step) {
|
||
|
|
if ($step->sane()) $out[$glyph] = $step->instruction();
|
||
|
|
}
|
||
|
|
return $out;
|
||
|
|
}
|
||
|
|
function segment_config() {
|
||
|
|
# Filter $this->close into categories based on the symbol_after_the_dot.
|
||
|
|
$f = array();
|
||
|
|
foreach ($this->close as $c) {
|
||
|
|
$p = $c->symbol_after_the_dot;
|
||
|
|
if (!$p) continue;
|
||
|
|
$f[$p->name][] = $c;
|
||
|
|
}
|
||
|
|
return $f;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class sym {
|
||
|
|
function __construct($name, $id) {
|
||
|
|
$this->name=$name;
|
||
|
|
$this->id=$id;
|
||
|
|
$this->term = true; # Until proven otherwise.
|
||
|
|
$this->rule = array();
|
||
|
|
$this->config = array();
|
||
|
|
$this->lambda = false;
|
||
|
|
$this->first = new set();
|
||
|
|
$this->left_prec = $this->right_prec = 0;
|
||
|
|
}
|
||
|
|
function summary() {
|
||
|
|
$out = '';
|
||
|
|
foreach ($this->rule as $rule) $out .= $rule->text()."\n";
|
||
|
|
return $out;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class rule {
|
||
|
|
function __construct($id, $sym, $rhs, $code, $look, $replace) {
|
||
|
|
$this->id = $id;
|
||
|
|
$this->sym = $sym;
|
||
|
|
$this->rhs = $rhs;
|
||
|
|
$this->code = $code;
|
||
|
|
$this->look = $look;
|
||
|
|
bug_unless(is_int($look));
|
||
|
|
$this->replace = $replace;
|
||
|
|
#$this->prec_sym = $prec_sym;
|
||
|
|
$this->prec = 0;
|
||
|
|
$this->first = array();
|
||
|
|
$this->epsilon = count($rhs);
|
||
|
|
}
|
||
|
|
function lhs_glyph() { return $this->sym->name; }
|
||
|
|
function determine_precedence() {
|
||
|
|
# We may eventually expand to allow explicit prec_symbol declarations.
|
||
|
|
# Until then, we'll go with the rightmost terminal, which is what
|
||
|
|
# BISON does. People probably expect that. The leftmost terminal
|
||
|
|
# is a reasonable alternative behaviour, but I don't see the big
|
||
|
|
# deal just now.
|
||
|
|
|
||
|
|
#$prec_sym = $this->prec_sym;
|
||
|
|
#if (!$prec_sym)
|
||
|
|
$prec_sym = $this->rightmost_terminal();
|
||
|
|
if (!$prec_sym) return;
|
||
|
|
$this->prec = $prec_sym->left_prec;
|
||
|
|
}
|
||
|
|
private function rightmost_terminal() {
|
||
|
|
$symbol = NULL;
|
||
|
|
$rhs = $this->rhs;
|
||
|
|
while ($rhs) {
|
||
|
|
$symbol = array_pop($rhs);
|
||
|
|
if ($symbol->term) break;
|
||
|
|
}
|
||
|
|
return $symbol;
|
||
|
|
}
|
||
|
|
function text() {
|
||
|
|
$t = "($this->id) ".$this->lhs_glyph().' :=';
|
||
|
|
foreach($this->rhs as $s) $t .= ' '.$s->name;
|
||
|
|
return $t;
|
||
|
|
}
|
||
|
|
function table(lime_language $lang) {
|
||
|
|
return array(
|
||
|
|
'symbol' => $this->lhs_glyph(),
|
||
|
|
'len' => $this->look,
|
||
|
|
'replace' => $this->replace,
|
||
|
|
'code' => $lang->fixup($this->code),
|
||
|
|
'text' => $this->text(),
|
||
|
|
);
|
||
|
|
}
|
||
|
|
function lambda() {
|
||
|
|
foreach ($this->rhs as $sym) if (!$sym->lambda) return false;
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
function find_first() {
|
||
|
|
$dot = count($this->rhs);
|
||
|
|
$last = $this->first[$dot] = new set();
|
||
|
|
while ($dot) {
|
||
|
|
$dot--;
|
||
|
|
$symbol_after_the_dot = $this->rhs[$dot];
|
||
|
|
$first = $symbol_after_the_dot->first->all();
|
||
|
|
bug_if(empty($first) and !$symbol_after_the_dot->lambda);
|
||
|
|
$set = new set($first);
|
||
|
|
if ($symbol_after_the_dot->lambda) {
|
||
|
|
$set->union($last);
|
||
|
|
if ($this->epsilon == $dot+1) $this->epsilon = $dot;
|
||
|
|
}
|
||
|
|
$last = $this->first[$dot] = $set;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
function teach_symbol_of_first_set() {
|
||
|
|
$go = false;
|
||
|
|
foreach ($this->rhs as $sym) {
|
||
|
|
if ($this->sym->first->union($sym->first)) $go = true;
|
||
|
|
if (!$sym->lambda) break;
|
||
|
|
}
|
||
|
|
return $go;
|
||
|
|
}
|
||
|
|
function lambda_from($dot) {
|
||
|
|
return $this->epsilon <= $dot;
|
||
|
|
}
|
||
|
|
function leftmost($follow) {
|
||
|
|
return new config($this, 0, $follow);
|
||
|
|
}
|
||
|
|
function dotted_text($dot) {
|
||
|
|
$out = $this->lhs_glyph().' :=';
|
||
|
|
$idx = -1;
|
||
|
|
foreach($this->rhs as $idx => $s) {
|
||
|
|
if ($idx == $dot) $out .= ' .';
|
||
|
|
$out .= ' '.$s->name;
|
||
|
|
}
|
||
|
|
if ($dot > $idx) $out .= ' .';
|
||
|
|
return $out;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class config {
|
||
|
|
function __construct($rule, $dot, $follow) {
|
||
|
|
$this->rule=$rule;
|
||
|
|
$this->dot = $dot;
|
||
|
|
$this->key = "$rule->id.$dot";
|
||
|
|
$this->rightmost = count($rule->rhs) <= $dot;
|
||
|
|
$this->symbol_after_the_dot = $this->rightmost ? null : $rule->rhs[$dot];
|
||
|
|
$this->_blink = array();
|
||
|
|
$this->follow = new set($follow);
|
||
|
|
$this->_flink= array();
|
||
|
|
bug_unless($this->rightmost or count($rule));
|
||
|
|
}
|
||
|
|
function text() {
|
||
|
|
$out = $this->rule->dotted_text($this->dot);
|
||
|
|
$out .= ' [ '.implode(' ', $this->follow->all()).' ]';
|
||
|
|
return $out;
|
||
|
|
}
|
||
|
|
function blink($config) {
|
||
|
|
$this->_blink[] = $config;
|
||
|
|
}
|
||
|
|
function next() {
|
||
|
|
bug_if($this->rightmost);
|
||
|
|
$c = new config($this->rule, $this->dot+1, array());
|
||
|
|
# Anything in the follow set for this config will also be in the next.
|
||
|
|
# However, we link it backwards because we might wind up selecting a
|
||
|
|
# pre-existing state, and the housekeeping is easier in the first half
|
||
|
|
# of the program. We'll fix it before doing the propagation.
|
||
|
|
$c->blink($this);
|
||
|
|
return $c;
|
||
|
|
}
|
||
|
|
function copy_links_from($that) {
|
||
|
|
foreach($that->_blink as $c) $this->blink($c);
|
||
|
|
}
|
||
|
|
function lambda() {
|
||
|
|
return $this->rule->lambda_from($this->dot);
|
||
|
|
}
|
||
|
|
function simple_follow() {
|
||
|
|
return $this->rule->first[$this->dot+1]->all();
|
||
|
|
}
|
||
|
|
function epsilon_follows() {
|
||
|
|
return $this->rule->lambda_from($this->dot+1);
|
||
|
|
}
|
||
|
|
function fixlinks() {
|
||
|
|
foreach ($this->_blink as $that) $that->_flink[] = $this;
|
||
|
|
$this->blink = array();
|
||
|
|
}
|
||
|
|
function dump() {
|
||
|
|
echo " * ";
|
||
|
|
echo $this->key.' : ';
|
||
|
|
echo $this->rule->dotted_text($this->dot);
|
||
|
|
echo $this->follow->text();
|
||
|
|
foreach ($this->_flink as $c) echo $c->key.' / ';
|
||
|
|
echo "\n";
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class lime {
|
||
|
|
var $parser_class = 'parser';
|
||
|
|
function __construct() {
|
||
|
|
$this->p_next = 1;
|
||
|
|
$this->sym = array();
|
||
|
|
$this->rule = array();
|
||
|
|
$this->start_symbol_set = array();
|
||
|
|
$this->state = array();
|
||
|
|
$this->stop = $this->sym('#');
|
||
|
|
#$err = $this->sym('error');
|
||
|
|
$err->term = false;
|
||
|
|
$this->lang = new lime_language_php();
|
||
|
|
}
|
||
|
|
function language() { return $this->lang; }
|
||
|
|
function build_parser() {
|
||
|
|
$this->add_start_rule();
|
||
|
|
foreach ($this->rule as $r) $r->determine_precedence();
|
||
|
|
$this->find_sym_lamdba();
|
||
|
|
$this->find_sym_first();
|
||
|
|
foreach ($this->rule as $rule) $rule->find_first();
|
||
|
|
$initial = $this->find_states();
|
||
|
|
$this->fixlinks();
|
||
|
|
# $this->dump_configurations();
|
||
|
|
$this->find_follow_sets();
|
||
|
|
foreach($this->state as $s) $s->find_reductions($this);
|
||
|
|
$i = $this->resolve_conflicts();
|
||
|
|
$a = $this->rule_table();
|
||
|
|
$qi = $initial->id;
|
||
|
|
return $this->lang->ptab_to_class($this->parser_class, compact('a', 'qi', 'i'));
|
||
|
|
}
|
||
|
|
function rule_table() {
|
||
|
|
$s = array();
|
||
|
|
foreach ($this->rule as $i => $r) {
|
||
|
|
$s[$i] = $r->table($this->lang);
|
||
|
|
}
|
||
|
|
return $s;
|
||
|
|
}
|
||
|
|
function add_rule($symbol, $rhs, $code) {
|
||
|
|
$this->add_raw_rule($symbol, $rhs, $code, count($rhs), true);
|
||
|
|
}
|
||
|
|
function trump_up_bogus_lhs($real) {
|
||
|
|
return "'$real'".count($this->rule);
|
||
|
|
}
|
||
|
|
function add_raw_rule($lhs, $rhs, $code, $look, $replace) {
|
||
|
|
$sym = $this->sym($lhs);
|
||
|
|
$sym->term=false;
|
||
|
|
if (empty($rhs)) $sym->lambda = true;
|
||
|
|
$rs = array();
|
||
|
|
foreach ($rhs as $str) $rs[] = $this->sym($str);
|
||
|
|
$rid = count($this->rule);
|
||
|
|
$r = new rule($rid, $sym, $rs, $code, $look, $replace);
|
||
|
|
$this->rule[$rid] = $r;
|
||
|
|
$sym->rule[] = $r;
|
||
|
|
}
|
||
|
|
function sym($str) {
|
||
|
|
if (!isset($this->sym[$str])) $this->sym[$str] = new sym($str, count($this->sym));
|
||
|
|
return $this->sym[$str];
|
||
|
|
}
|
||
|
|
function summary() {
|
||
|
|
$out = '';
|
||
|
|
foreach ($this->sym as $sym) if (!$sym->term) $out .= $sym->summary();
|
||
|
|
return $out;
|
||
|
|
}
|
||
|
|
private function find_sym_lamdba() {
|
||
|
|
do {
|
||
|
|
$go = false;
|
||
|
|
foreach ($this->sym as $sym) if (!$sym->lambda) {
|
||
|
|
foreach ($sym->rule as $rule) if ($rule->lambda()) {
|
||
|
|
$go = true;
|
||
|
|
$sym->lambda = true;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
} while ($go);
|
||
|
|
}
|
||
|
|
private function teach_terminals_first_set() {
|
||
|
|
foreach ($this->sym as $sym) if ($sym->term) $sym->first->add($sym->name);
|
||
|
|
}
|
||
|
|
private function find_sym_first() {
|
||
|
|
$this->teach_terminals_first_set();
|
||
|
|
do {
|
||
|
|
$go = false;
|
||
|
|
foreach ($this->rule as $r) if ($r->teach_symbol_of_first_set()) $go = true;
|
||
|
|
} while ($go);
|
||
|
|
}
|
||
|
|
function add_start_rule() {
|
||
|
|
$rewrite = new lime_rewrite("'start'");
|
||
|
|
$rhs = new lime_rhs();
|
||
|
|
$rhs->add(new lime_glyph($this->deduce_start_symbol()->name, NULL));
|
||
|
|
#$rhs->add(new lime_glyph($this->stop->name, NULL));
|
||
|
|
$rewrite->add_rhs($rhs);
|
||
|
|
$rewrite->update($this);
|
||
|
|
}
|
||
|
|
private function deduce_start_symbol() {
|
||
|
|
$candidate = current($this->start_symbol_set);
|
||
|
|
# Did the person try to set a start symbol at all?
|
||
|
|
if (!$candidate) return $this->first_rule_lhs();
|
||
|
|
# Do we actually have such a symbol on the left of a rule?
|
||
|
|
if ($candidate->terminal) return $this->first_rule_lhs();
|
||
|
|
# Ok, it's a decent choice. We need to return the symbol entry.
|
||
|
|
return $this->sym($candidate);
|
||
|
|
}
|
||
|
|
private function first_rule_lhs() {
|
||
|
|
reset($this->rule);
|
||
|
|
$r = current($this->rule);
|
||
|
|
return $r->sym;
|
||
|
|
}
|
||
|
|
function find_states() {
|
||
|
|
/*
|
||
|
|
Build an initial state. This is a recursive process which digs out
|
||
|
|
the LR(0) state graph.
|
||
|
|
*/
|
||
|
|
$start_glyph = "'start'";
|
||
|
|
$sym = $this->sym($start_glyph);
|
||
|
|
$basis = array();
|
||
|
|
foreach($sym->rule as $rule) {
|
||
|
|
$c = $rule->leftmost(array('#'));
|
||
|
|
$basis[$c->key] = $c;
|
||
|
|
}
|
||
|
|
$initial = $this->get_state($basis);
|
||
|
|
$initial->add_accept($sym);
|
||
|
|
return $initial;
|
||
|
|
}
|
||
|
|
function get_state($basis) {
|
||
|
|
$key = array_keys($basis);
|
||
|
|
sort($key);
|
||
|
|
$key = implode(' ', $key);
|
||
|
|
if (isset($this->state[$key])) {
|
||
|
|
# Copy all the links around...
|
||
|
|
$state = $this->state[$key];
|
||
|
|
foreach($basis as $config) $state->close[$config->key]->copy_links_from($config);
|
||
|
|
return $state;
|
||
|
|
} else {
|
||
|
|
$close = $this->state_closure($basis);
|
||
|
|
$this->state[$key] = $state = new state(count($this->state), $key, $close);
|
||
|
|
$this->build_shifts($state);
|
||
|
|
return $state;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
private function state_closure($q) {
|
||
|
|
# $q is a list of config.
|
||
|
|
$close = array();
|
||
|
|
while ($config = array_pop($q)) {
|
||
|
|
if (isset($close[$config->key])) {
|
||
|
|
$close[$config->key]->copy_links_from($config);
|
||
|
|
$close[$config->key]->follow->union($config->follow);
|
||
|
|
continue;
|
||
|
|
}
|
||
|
|
$close[$config->key] = $config;
|
||
|
|
|
||
|
|
$symbol_after_the_dot = $config->symbol_after_the_dot;
|
||
|
|
if (!$symbol_after_the_dot) continue;
|
||
|
|
|
||
|
|
if (! $symbol_after_the_dot->term) {
|
||
|
|
foreach ($symbol_after_the_dot->rule as $r) {
|
||
|
|
$station = $r->leftmost($config->simple_follow());
|
||
|
|
if ($config->epsilon_follows()) $station->blink($config);
|
||
|
|
$q[] = $station;
|
||
|
|
}
|
||
|
|
# The following turned out to be wrong. Don't do it.
|
||
|
|
#if ($symbol_after_the_dot->lambda) {
|
||
|
|
# $q[] = $config->next();
|
||
|
|
#}
|
||
|
|
}
|
||
|
|
|
||
|
|
}
|
||
|
|
return $close;
|
||
|
|
}
|
||
|
|
function build_shifts($state) {
|
||
|
|
foreach ($state->segment_config() as $glyph => $segment) {
|
||
|
|
$basis = array();
|
||
|
|
foreach ($segment as $preshift) {
|
||
|
|
$postshift = $preshift->next();
|
||
|
|
$basis[$postshift->key] = $postshift;
|
||
|
|
}
|
||
|
|
$dest = $this->get_state($basis);
|
||
|
|
$state->add_shift($this->sym($glyph), $dest);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
function fixlinks() {
|
||
|
|
foreach ($this->state as $s) foreach ($s->close as $c) $c->fixlinks();
|
||
|
|
}
|
||
|
|
function find_follow_sets() {
|
||
|
|
$q = array();
|
||
|
|
foreach ($this->state as $s) foreach ($s->close as $c) $q[] = $c;
|
||
|
|
while ($q) {
|
||
|
|
$c = array_shift($q);
|
||
|
|
foreach ($c->_flink as $d) {
|
||
|
|
if ($d->follow->union($c->follow)) $q[] = $d;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
private function set_assoc($ss, $l, $r) {
|
||
|
|
$p = ($this->p_next++)*2;
|
||
|
|
foreach ($ss as $glyph) {
|
||
|
|
$s = $this->sym($glyph);
|
||
|
|
$s->left_prec = $p+$l;
|
||
|
|
$s->right_prec = $p+$r;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
function left_assoc($ss) { $this->set_assoc($ss, 1, 0); }
|
||
|
|
function right_assoc($ss) { $this->set_assoc($ss, 0, 1); }
|
||
|
|
function non_assoc($ss) { $this->set_assoc($ss, 0, 0); }
|
||
|
|
private function resolve_conflicts() {
|
||
|
|
# For each state, try to find one and only one
|
||
|
|
# thing to do for any given lookahead.
|
||
|
|
$i = array();
|
||
|
|
foreach ($this->state as $s) $i[$s->id] = $s->resolve_conflicts();
|
||
|
|
return $i;
|
||
|
|
}
|
||
|
|
function dump_configurations() {
|
||
|
|
foreach ($this->state as $q) $q->dump();
|
||
|
|
}
|
||
|
|
function dump_first_sets() {
|
||
|
|
foreach ($this->sym as $s) {
|
||
|
|
echo " * ";
|
||
|
|
echo $s->name.' : ';
|
||
|
|
echo $s->first->text();
|
||
|
|
echo "\n";
|
||
|
|
}
|
||
|
|
}
|
||
|
|
function add_rule_with_actions($lhs, $rhs) {
|
||
|
|
# First, make sure this thing is well-formed.
|
||
|
|
if(!is_object(end($rhs))) $rhs[] = new cf_action('');
|
||
|
|
# Now, split it into chunks based on the actions.
|
||
|
|
$look = -1;
|
||
|
|
$subrule = array();
|
||
|
|
$subsymbol = '';
|
||
|
|
while (count($rhs)) {
|
||
|
|
$it = array_shift($rhs);
|
||
|
|
$look ++;
|
||
|
|
if (is_string($it)) {
|
||
|
|
$subrule[] = $it;
|
||
|
|
} else {
|
||
|
|
$code = $it->code;
|
||
|
|
# It's an action.
|
||
|
|
# Is it the last one?
|
||
|
|
if (count($rhs)) {
|
||
|
|
# no.
|
||
|
|
$subsymbol = $this->trump_up_bogus_lhs($lhs);
|
||
|
|
$this->add_raw_rule($subsymbol, $subrule, $code, $look, false);
|
||
|
|
$subrule = array($subsymbol);
|
||
|
|
} else {
|
||
|
|
# yes.
|
||
|
|
$this->add_raw_rule($lhs, $subrule, $code, $look, true);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
function pragma($type, $args) {
|
||
|
|
switch ($type) {
|
||
|
|
case 'left':
|
||
|
|
$this->left_assoc($args);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case 'right':
|
||
|
|
$this->right_assoc($args);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case 'nonassoc':
|
||
|
|
$this->non_assoc($args);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case 'start':
|
||
|
|
$this->start_symbol_set = $args;
|
||
|
|
break;
|
||
|
|
|
||
|
|
case 'class':
|
||
|
|
$this->parser_class = $args[0];
|
||
|
|
break;
|
||
|
|
|
||
|
|
default:
|
||
|
|
emit(sprintf("Bad Parser Pragma: (%s)", $type));
|
||
|
|
exit(1);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class lime_language {}
|
||
|
|
class lime_language_php extends lime_language {
|
||
|
|
private function result_code($expr) { return "\$result = $expr;\n"; }
|
||
|
|
function default_result() { return $this->result_code('reset($tokens)'); }
|
||
|
|
function result_pos($pos) { return $this->result_code(lime_token_reference($pos)); }
|
||
|
|
function bind($name, $pos) { return "\$$name =& \$tokens[$pos];\n"; }
|
||
|
|
function fixup($code) {
|
||
|
|
$code = preg_replace_callback('/\\$(\d+)/', 'lime_token_reference_callback', $code);
|
||
|
|
$code = preg_replace('/\\$\\$/', '$result', $code);
|
||
|
|
return $code;
|
||
|
|
}
|
||
|
|
function to_php($code) {
|
||
|
|
return $code;
|
||
|
|
}
|
||
|
|
function ptab_to_class($parser_class, $ptab) {
|
||
|
|
$code = "class $parser_class extends lime_parser {\n";
|
||
|
|
$code .= 'var $qi = '.var_export($ptab['qi'], true).";\n";
|
||
|
|
$code .= 'var $i = '.var_export($ptab['i'], true).";\n";
|
||
|
|
|
||
|
|
|
||
|
|
$rc = array();
|
||
|
|
$method = array();
|
||
|
|
$rules = array();
|
||
|
|
foreach($ptab['a'] as $k => $a) {
|
||
|
|
$symbol = preg_replace('/[^\w]/', '', $a['symbol']);
|
||
|
|
$rn = ++$rc[$symbol];
|
||
|
|
$mn = "reduce_${k}_${symbol}_${rn}";
|
||
|
|
$method[$k] = $mn;
|
||
|
|
$comment = "#\n# $a[text]\n#\n";
|
||
|
|
$php = $this->to_php($a['code']);
|
||
|
|
$code .= "function $mn(".LIME_CALL_PROTOCOL.") {\n$comment$php\n}\n\n";
|
||
|
|
|
||
|
|
|
||
|
|
unset($a['code']);
|
||
|
|
unset($a['text']);
|
||
|
|
$rules[$k] = $a;
|
||
|
|
}
|
||
|
|
|
||
|
|
$code .= 'var $method = '.var_export($method, true).";\n";
|
||
|
|
$code .= 'var $a = '.var_export($rules, true).";\n";
|
||
|
|
|
||
|
|
|
||
|
|
|
||
|
|
$code .= "}\n";
|
||
|
|
#echo $code;
|
||
|
|
return $code;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class lime_rhs {
|
||
|
|
function __construct() {
|
||
|
|
/**
|
||
|
|
Construct and add glyphs and actions in whatever order.
|
||
|
|
Then, add this to a lime_rewrite.
|
||
|
|
|
||
|
|
Don't call install_rule.
|
||
|
|
The rewrite will do that for you when you "update" with it.
|
||
|
|
*/
|
||
|
|
$this->rhs = array();
|
||
|
|
}
|
||
|
|
function add($slot) {
|
||
|
|
bug_unless($slot instanceof lime_slot);
|
||
|
|
$this->rhs[] = $slot;
|
||
|
|
}
|
||
|
|
function install_rule(lime $lime, $lhs) {
|
||
|
|
# This is the part that has to break the rule into subrules if necessary.
|
||
|
|
$rhs = $this->rhs;
|
||
|
|
# First, make sure this thing is well-formed.
|
||
|
|
if (!(end($rhs) instanceof lime_action)) $rhs[] = new lime_action('', NULL);
|
||
|
|
# Now, split it into chunks based on the actions.
|
||
|
|
|
||
|
|
$lang = $lime->language();
|
||
|
|
$result_code = $lang->default_result();
|
||
|
|
$look = -1;
|
||
|
|
$subrule = array();
|
||
|
|
$subsymbol = '';
|
||
|
|
$preamble = '';
|
||
|
|
while (count($rhs)) {
|
||
|
|
$it = array_shift($rhs);
|
||
|
|
$look ++;
|
||
|
|
if ($it instanceof lime_glyph) {
|
||
|
|
$subrule[] = $it->data;
|
||
|
|
} elseif ($it instanceof lime_action) {
|
||
|
|
$code = $it->data;
|
||
|
|
# It's an action.
|
||
|
|
# Is it the last one?
|
||
|
|
if (count($rhs)) {
|
||
|
|
# no.
|
||
|
|
$subsymbol = $lime->trump_up_bogus_lhs($lhs);
|
||
|
|
$action = $lang->default_result().$preamble.$code;
|
||
|
|
$lime->add_raw_rule($subsymbol, $subrule, $action, $look, false);
|
||
|
|
$subrule = array($subsymbol);
|
||
|
|
} else {
|
||
|
|
# yes.
|
||
|
|
$action = $result_code.$preamble.$code;
|
||
|
|
$lime->add_raw_rule($lhs, $subrule, $action, $look, true);
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
impossible();
|
||
|
|
}
|
||
|
|
if ($it->name == '$') $result_code = $lang->result_pos($look);
|
||
|
|
elseif ($it->name) $preamble .= $lang->bind($it->name, $look);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class lime_rewrite {
|
||
|
|
function __construct($glyph) {
|
||
|
|
/**
|
||
|
|
Construct one of these with the name of the lhs.
|
||
|
|
Add some rhs-es to it.
|
||
|
|
Finally, "update" the lime you're building.
|
||
|
|
*/
|
||
|
|
$this->glyph = $glyph;
|
||
|
|
$this->rhs = array();
|
||
|
|
}
|
||
|
|
function add_rhs($rhs) {
|
||
|
|
bug_unless($rhs instanceof lime_rhs);
|
||
|
|
$this->rhs[] = $rhs;
|
||
|
|
}
|
||
|
|
function update(lime $lime) {
|
||
|
|
foreach ($this->rhs as $rhs) {
|
||
|
|
$rhs->install_rule($lime, $this->glyph);
|
||
|
|
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class lime_slot {
|
||
|
|
/**
|
||
|
|
This keeps track of one position in an rhs.
|
||
|
|
We specialize to handle actions and glyphs.
|
||
|
|
If there is a name for the slot, we store it here.
|
||
|
|
Later on, this structure will be consulted in the formation of
|
||
|
|
actual production rules.
|
||
|
|
*/
|
||
|
|
function __construct($data, $name) {
|
||
|
|
$this->data = $data;
|
||
|
|
$this->name = $name;
|
||
|
|
}
|
||
|
|
function preamble($pos) {
|
||
|
|
if (strlen($this->name) > 0) {
|
||
|
|
return "\$$this->name =& \$tokens[$pos];\n";
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
class lime_glyph extends lime_slot {}
|
||
|
|
class lime_action extends lime_slot {}
|
||
|
|
function lime_bootstrap() {
|
||
|
|
|
||
|
|
/*
|
||
|
|
|
||
|
|
This function isn't too terribly interesting to the casual observer.
|
||
|
|
You're probably better off looking at parse_lime_grammar() instead.
|
||
|
|
|
||
|
|
Ok, if you insist, I'll explain.
|
||
|
|
|
||
|
|
The input to Lime is a CFG parser definition. That definition is
|
||
|
|
written in some language. (The Lime language, to be exact.)
|
||
|
|
Anyway, I have to parse the Lime language and compile it into a
|
||
|
|
very complex data structure from which a parser is eventually
|
||
|
|
built. What better way than to use Lime itself to parse its own
|
||
|
|
language? Well, it's almost that simple, but not quite.
|
||
|
|
|
||
|
|
The Lime language is fairly potent, but a restricted subset of
|
||
|
|
its features was used to write a metagrammar. Then, I hand-translated
|
||
|
|
that metagrammar into another form which is easy to snarf up.
|
||
|
|
In the process of reading that simplified form, this function
|
||
|
|
builds the same sort of data structure that later gets turned into
|
||
|
|
a parser. The last step is to run the parser generation algorithm,
|
||
|
|
eval() the resulting PHP code, and voila! With no hard work, I can
|
||
|
|
suddenly read and comprehend the full range of the Lime language
|
||
|
|
without ever having written an algorithm to do so. It feels like magic.
|
||
|
|
|
||
|
|
*/
|
||
|
|
|
||
|
|
$bootstrap = LIME_DIR."/lime.bootstrap";
|
||
|
|
$lime = new lime();
|
||
|
|
$lime->parser_class = 'lime_metaparser';
|
||
|
|
$rhs = array();
|
||
|
|
bug_unless(is_readable($bootstrap));
|
||
|
|
foreach(file($bootstrap) as $l) {
|
||
|
|
$a = explode(":", $l, 2);
|
||
|
|
if (count($a) == 2) {
|
||
|
|
list($pattern, $code) = $a;
|
||
|
|
$sl = new lime_rhs();
|
||
|
|
$pattern = trim($pattern);
|
||
|
|
if (strlen($pattern)>0) {
|
||
|
|
foreach (explode(' ', $pattern) as $glyph) $sl->add(new lime_glyph($glyph, NULL));
|
||
|
|
}
|
||
|
|
$sl->add(new lime_action($code, NULL));
|
||
|
|
$rhs[] = $sl;
|
||
|
|
} else {
|
||
|
|
$m = preg_match('/^to (\w+)$/', $l, $r);
|
||
|
|
if ($m == 0) continue;
|
||
|
|
$g = $r[1];
|
||
|
|
$rw = new lime_rewrite($g);
|
||
|
|
foreach($rhs as $b) $rw->add_rhs($b);
|
||
|
|
$rw->update($lime);
|
||
|
|
$rhs = array();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
$parser_code = $lime->build_parser();
|
||
|
|
eval($parser_code);
|
||
|
|
}
|
||
|
|
|
||
|
|
class voodoo_scanner extends flex_scanner {
|
||
|
|
/*
|
||
|
|
|
||
|
|
The voodoo is in the way I do lexical processing on grammar definition
|
||
|
|
files. They contain embedded bits of PHP, and it's important to keep
|
||
|
|
track of things like strings, comments, and matched braces. It seemed
|
||
|
|
like an ideal problem to solve with GNU flex, so I wrote a little
|
||
|
|
scanner in flex and C to dig out the tokens for me. Of course, I need
|
||
|
|
the tokens in PHP, so I designed a simple binary wrapper for them which
|
||
|
|
also contains line-number information, guaranteed to help out if you
|
||
|
|
write a grammar which surprises the parser in any manner.
|
||
|
|
|
||
|
|
*/
|
||
|
|
function executable() { return LIME_DIR.'/lime_scan_tokens'; }
|
||
|
|
}
|
||
|
|
|
||
|
|
function parse_lime_grammar($path) {
|
||
|
|
/*
|
||
|
|
|
||
|
|
This is a good function to read because it teaches you how to interface
|
||
|
|
with a Lime parser. I've tried to isolate out the bits that aren't
|
||
|
|
instructive in that regard.
|
||
|
|
|
||
|
|
*/
|
||
|
|
if (!class_exists('lime_metaparser')) lime_bootstrap();
|
||
|
|
|
||
|
|
$parse_engine = new parse_engine(new lime_metaparser());
|
||
|
|
$scanner = new voodoo_scanner($path);
|
||
|
|
try {
|
||
|
|
# The result of parsing a Lime grammar is a Lime object.
|
||
|
|
$lime = $scanner->feed($parse_engine);
|
||
|
|
# Calling its build_parser() method gets the output PHP code.
|
||
|
|
return $lime->build_parser();
|
||
|
|
} catch (parse_error $e) {
|
||
|
|
die ($e->getMessage()." in $path line $scanner->lineno.\n");
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
if ($_SERVER['argv']) {
|
||
|
|
$code = '';
|
||
|
|
array_shift($_SERVER['argv']); # Strip out the program name.
|
||
|
|
foreach ($_SERVER['argv'] as $path) {
|
||
|
|
$code .= parse_lime_grammar($path);
|
||
|
|
}
|
||
|
|
|
||
|
|
echo "<?php\n\n";
|
||
|
|
?>
|
||
|
|
|
||
|
|
/*
|
||
|
|
|
||
|
|
DON'T EDIT THIS FILE!
|
||
|
|
|
||
|
|
This file was automatically generated by the Lime parser generator.
|
||
|
|
The real source code you should be looking at is in one or more
|
||
|
|
grammar files in the Lime format.
|
||
|
|
|
||
|
|
THE ONLY REASON TO LOOK AT THIS FILE is to see where in the grammar
|
||
|
|
file that your error happened, because there are enough comments to
|
||
|
|
help you debug your grammar.
|
||
|
|
|
||
|
|
If you ignore this warning, you're shooting yourself in the brain,
|
||
|
|
not the foot.
|
||
|
|
|
||
|
|
*/
|
||
|
|
|
||
|
|
<?php
|
||
|
|
echo $code;
|
||
|
|
}
|