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libphutil/src/parser/__tests__/PhutilParserGeneratorTestCase.php
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PhutilParserGeneratorTestCase.php
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<?php
final class PhutilParserGeneratorTestCase extends PhutilTestCase {
public function testBogusGrammar() {
$generator = id(new PhutilParserGenerator())
->setTerminals(array('a'))
->setStartRule('S')
->setRules(
array(
'S' => 'a b',
));
$caught = null;
try {
// Expect "b is not a rule or terminal".
$generator->processGrammar();
} catch (PhutilParserGeneratorUnknownSymbolException $ex) {
$caught = $ex;
}
$this->assertTrue($caught instanceof Exception);
}
public function testBadStartRule() {
$generator = id(new PhutilParserGenerator())
->setTerminals(array('a'))
->setStartRule('Q')
->setRules(
array(
'S' => 'a',
));
$caught = null;
try {
// Expect "no start rule Q".
$generator->processGrammar();
} catch (PhutilParserGeneratorUnknownSymbolException $ex) {
$caught = $ex;
}
$this->assertTrue($caught instanceof Exception);
}
public function testMessySymbols() {
// This is testing that internal defaults are correctly changed when they
// would conflict with the provided grammar. This is a messy test which
// relies on a lot of implementation details.
$generator = id(new PhutilParserGenerator())
->setTerminals(array('(init)', 'x', 'y', 'start', '(end)'))
->setStartRule('(epsilon)')
->setRules(
array(
'(epsilon)' => array(
array('s p a c e s'),
),
's p a c e s' => '(init) x start (end-of-file) y',
'(end-of-file)' => array(
'(end)',
null,
),
))
->processGrammar();
$rules = $generator->inspectRules();
$init = $generator->getInitSymbol();
$eof = $generator->getEOFSymbol();
$epsilon = $generator->getEpsilonSymbol();
$end = $generator->getEndSymbol();
$this->assertFalse($init == '(init)');
$this->assertFalse($eof == '(end-of-file)');
$this->assertFalse($epsilon == '(epsilon)');
$this->assertFalse($end == '(end)');
$keys = array_keys($rules);
$expect = array('(end-of-file)', '(epsilon)', 's p a c e s', $init);
sort($keys);
sort($expect);
$this->assertEqual($keys, $expect);
$this->assertEqual(
array(
array('s p a c e s', $end),
),
$rules['(epsilon)']);
$this->assertEqual(
array(
array('(end)', $end),
array($epsilon, $end),
),
$rules['(end-of-file)']);
}
public function testUnreachableTerminal() {
$generator = id(new PhutilParserGenerator())
->setTerminals(array('x', 'y'))
->setStartRule('S')
->setRules(
array(
'S' => 'x',
));
$caught = null;
try {
$generator->processGrammar();
} catch (PhutilParserGeneratorUnreachableTerminalException $ex) {
$caught = $ex;
}
$this->assertTrue($caught instanceof Exception);
}
public function testUnreachableRule() {
$generator = id(new PhutilParserGenerator())
->setTerminals(array('x'))
->setStartRule('S')
->setRules(
array(
'S' => 'x',
'A' => 'B',
'B' => 'x',
));
$caught = null;
try {
$generator->processGrammar();
} catch (PhutilParserGeneratorUnreachableRuleException $ex) {
$caught = $ex;
}
$this->assertTrue($caught instanceof Exception);
}
public function testIrreducibleGrammars() {
$tests = array(
'trivially irreducible' => array(
true,
array(
'S' => array('E', 'x'),
'E' => 'E',
),
),
'nontrivially irreducible' => array(
true,
array(
'S' => array('X', 'x'),
'X' => 'Y',
'Y' => 'Z',
'Z' => 'X',
),
),
'left-recursive reducible' => array(
false,
array(
'S' => 'E',
'E' => array('E x', 'x'),
),
),
'right-recursive reducible' => array(
false,
array(
'S' => 'E',
'E' => array('x', 'x E'),
),
),
);
foreach ($tests as $test) {
list($expect, $rules) = $test;
$generator = id(new PhutilParserGenerator())
->setTerminals(array('x'))
->setStartRule('S')
->setRules($rules);
$caught = null;
try {
$generator->processGrammar();
} catch (PhutilParserGeneratorIrreducibleRuleException $ex) {
$caught = $ex;
}
$this->assertEqual($expect, ($caught instanceof Exception));
}
}
public function testFirst() {
$generator = $this->buildABCGenerator()->processGrammar();
$first = $generator->inspectFirstTable();
ksort($first);
foreach ($first as $key => $table) {
ksort($table);
$first[$key] = $table;
}
$this->assertEqual(
array(
'A' => array(
'(epsilon)' => true,
'a' => true,
'b' => true,
),
'B' => array(
'c' => true,
),
'C' => array(
'(epsilon)' => true,
'b' => true,
),
'S' => array(
'a' => true,
'b' => true,
'c' => true,
),
),
$first);
}
public function testStates() {
$generator = id(new PhutilParserGenerator())
->setTerminals(array('a', 'b'))
->setStartRule('S')
->setRules(
array(
'S' => 'X X',
'X' => array(
'a X',
'b',
),
))
->processGrammar();
$this->assertTrue(true);
}
public function testETParser() {
$generator = $this->buildETGenerator()->processGrammar();
$result = $generator->parseTokens(
array(
array('n', 3),
array('+', '+'),
array('n', 5),
),
array($this, 'didReduceET'));
$this->assertEqual(8, $result);
}
public function didReduceET($rule, $production, array $tokens) {
switch ($rule) {
case 'S':
return $tokens[0];
case 'E':
switch ($production) {
case 0:
return $tokens[0] + $tokens[2];
case 1:
return $tokens[0];
}
break;
case 'T':
switch ($production) {
case 0:
return $tokens[1];
case 1:
return $tokens[0][1];
}
break;
}
throw new Exception('Unexpected rule in ET grammar.');
}
private function buildABCGenerator() {
$terminals = array(
'a',
'b',
'c',
);
$rules = array(
'S' => 'A B',
'A' => array('C a', null),
'B' => array('B a A C', 'c'),
'C' => array('b', null),
);
$generator = id(new PhutilParserGenerator())
->setTerminals($terminals)
->setStartRule('S')
->setRules($rules);
return $generator;
}
private function buildETGenerator() {
// This grammar and the corresponding tests are based on:
// http://dragonbook.stanford.edu/lecture-notes/Stanford-CS143/08-Bottom-Up-Parsing.pdf
// http://dragonbook.stanford.edu/lecture-notes/Stanford-CS143/09-SLR-Parsing.pdf
$terminals = array(
'(',
'n',
')',
'+',
);
$rules = array(
'S' => 'E',
'E' => array('E + T', 'T'),
'T' => array('( E )', 'n'),
);
$generator = id(new PhutilParserGenerator())
->setTerminals($terminals)
->setStartRule('S')
->setRules($rules);
return $generator;
}
}
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