<?php
namespace JmesPath;
/**
* Tokenizes JMESPath expressions
*/
class Lexer
{
const T_DOT = 'dot';
const T_STAR = 'star';
const T_COMMA = 'comma';
const T_COLON = 'colon';
const T_CURRENT = 'current';
const T_EXPREF = 'expref';
const T_LPAREN = 'lparen';
const T_RPAREN = 'rparen';
const T_LBRACE = 'lbrace';
const T_RBRACE = 'rbrace';
const T_LBRACKET = 'lbracket';
const T_RBRACKET = 'rbracket';
const T_FLATTEN = 'flatten';
const T_IDENTIFIER = 'identifier';
const T_NUMBER = 'number';
const T_QUOTED_IDENTIFIER = 'quoted_identifier';
const T_UNKNOWN = 'unknown';
const T_PIPE = 'pipe';
const T_OR = 'or';
const T_AND = 'and';
const T_NOT = 'not';
const T_FILTER = 'filter';
const T_LITERAL = 'literal';
const T_EOF = 'eof';
const T_COMPARATOR = 'comparator';
const STATE_IDENTIFIER = 0;
const STATE_NUMBER = 1;
const STATE_SINGLE_CHAR = 2;
const STATE_WHITESPACE = 3;
const STATE_STRING_LITERAL = 4;
const STATE_QUOTED_STRING = 5;
const STATE_JSON_LITERAL = 6;
const STATE_LBRACKET = 7;
const STATE_PIPE = 8;
const STATE_LT = 9;
const STATE_GT = 10;
const STATE_EQ = 11;
const STATE_NOT = 12;
const STATE_AND = 13;
/** @var array We know what token we are consuming based on each char */
private static $transitionTable = [
'<' => self::STATE_LT,
'>' => self::STATE_GT,
'=' => self::STATE_EQ,
'!' => self::STATE_NOT,
'[' => self::STATE_LBRACKET,
'|' => self::STATE_PIPE,
'&' => self::STATE_AND,
'`' => self::STATE_JSON_LITERAL,
'"' => self::STATE_QUOTED_STRING,
"'" => self::STATE_STRING_LITERAL,
'-' => self::STATE_NUMBER,
'0' => self::STATE_NUMBER,
'1' => self::STATE_NUMBER,
'2' => self::STATE_NUMBER,
'3' => self::STATE_NUMBER,
'4' => self::STATE_NUMBER,
'5' => self::STATE_NUMBER,
'6' => self::STATE_NUMBER,
'7' => self::STATE_NUMBER,
'8' => self::STATE_NUMBER,
'9' => self::STATE_NUMBER,
' ' => self::STATE_WHITESPACE,
"\t" => self::STATE_WHITESPACE,
"\n" => self::STATE_WHITESPACE,
"\r" => self::STATE_WHITESPACE,
'.' => self::STATE_SINGLE_CHAR,
'*' => self::STATE_SINGLE_CHAR,
']' => self::STATE_SINGLE_CHAR,
',' => self::STATE_SINGLE_CHAR,
':' => self::STATE_SINGLE_CHAR,
'@' => self::STATE_SINGLE_CHAR,
'(' => self::STATE_SINGLE_CHAR,
')' => self::STATE_SINGLE_CHAR,
'{' => self::STATE_SINGLE_CHAR,
'}' => self::STATE_SINGLE_CHAR,
'_' => self::STATE_IDENTIFIER,
'A' => self::STATE_IDENTIFIER,
'B' => self::STATE_IDENTIFIER,
'C' => self::STATE_IDENTIFIER,
'D' => self::STATE_IDENTIFIER,
'E' => self::STATE_IDENTIFIER,
'F' => self::STATE_IDENTIFIER,
'G' => self::STATE_IDENTIFIER,
'H' => self::STATE_IDENTIFIER,
'I' => self::STATE_IDENTIFIER,
'J' => self::STATE_IDENTIFIER,
'K' => self::STATE_IDENTIFIER,
'L' => self::STATE_IDENTIFIER,
'M' => self::STATE_IDENTIFIER,
'N' => self::STATE_IDENTIFIER,
'O' => self::STATE_IDENTIFIER,
'P' => self::STATE_IDENTIFIER,
'Q' => self::STATE_IDENTIFIER,
'R' => self::STATE_IDENTIFIER,
'S' => self::STATE_IDENTIFIER,
'T' => self::STATE_IDENTIFIER,
'U' => self::STATE_IDENTIFIER,
'V' => self::STATE_IDENTIFIER,
'W' => self::STATE_IDENTIFIER,
'X' => self::STATE_IDENTIFIER,
'Y' => self::STATE_IDENTIFIER,
'Z' => self::STATE_IDENTIFIER,
'a' => self::STATE_IDENTIFIER,
'b' => self::STATE_IDENTIFIER,
'c' => self::STATE_IDENTIFIER,
'd' => self::STATE_IDENTIFIER,
'e' => self::STATE_IDENTIFIER,
'f' => self::STATE_IDENTIFIER,
'g' => self::STATE_IDENTIFIER,
'h' => self::STATE_IDENTIFIER,
'i' => self::STATE_IDENTIFIER,
'j' => self::STATE_IDENTIFIER,
'k' => self::STATE_IDENTIFIER,
'l' => self::STATE_IDENTIFIER,
'm' => self::STATE_IDENTIFIER,
'n' => self::STATE_IDENTIFIER,
'o' => self::STATE_IDENTIFIER,
'p' => self::STATE_IDENTIFIER,
'q' => self::STATE_IDENTIFIER,
'r' => self::STATE_IDENTIFIER,
's' => self::STATE_IDENTIFIER,
't' => self::STATE_IDENTIFIER,
'u' => self::STATE_IDENTIFIER,
'v' => self::STATE_IDENTIFIER,
'w' => self::STATE_IDENTIFIER,
'x' => self::STATE_IDENTIFIER,
'y' => self::STATE_IDENTIFIER,
'z' => self::STATE_IDENTIFIER,
];
/** @var array Valid identifier characters after first character */
private $validIdentifier = [
'A' => true, 'B' => true, 'C' => true, 'D' => true, 'E' => true,
'F' => true, 'G' => true, 'H' => true, 'I' => true, 'J' => true,
'K' => true, 'L' => true, 'M' => true, 'N' => true, 'O' => true,
'P' => true, 'Q' => true, 'R' => true, 'S' => true, 'T' => true,
'U' => true, 'V' => true, 'W' => true, 'X' => true, 'Y' => true,
'Z' => true, 'a' => true, 'b' => true, 'c' => true, 'd' => true,
'e' => true, 'f' => true, 'g' => true, 'h' => true, 'i' => true,
'j' => true, 'k' => true, 'l' => true, 'm' => true, 'n' => true,
'o' => true, 'p' => true, 'q' => true, 'r' => true, 's' => true,
't' => true, 'u' => true, 'v' => true, 'w' => true, 'x' => true,
'y' => true, 'z' => true, '_' => true, '0' => true, '1' => true,
'2' => true, '3' => true, '4' => true, '5' => true, '6' => true,
'7' => true, '8' => true, '9' => true,
];
/** @var array Valid number characters after the first character */
private $numbers = [
'0' => true, '1' => true, '2' => true, '3' => true, '4' => true,
'5' => true, '6' => true, '7' => true, '8' => true, '9' => true
];
/** @var array Map of simple single character tokens */
private $simpleTokens = [
'.' => self::T_DOT,
'*' => self::T_STAR,
']' => self::T_RBRACKET,
',' => self::T_COMMA,
':' => self::T_COLON,
'@' => self::T_CURRENT,
'(' => self::T_LPAREN,
')' => self::T_RPAREN,
'{' => self::T_LBRACE,
'}' => self::T_RBRACE,
];
/**
* Tokenize the JMESPath expression into an array of tokens hashes that
* contain a 'type', 'value', and 'key'.
*
* @param string $input JMESPath input
*
* @return array
* @throws SyntaxErrorException
*/
public function tokenize($input)
{
$tokens = [];
if ($input === '') {
goto eof;
}
$chars = str_split($input);
while (false !== ($current = current($chars))) {
// Every character must be in the transition character table.
if (!isset(self::$transitionTable[$current])) {
$tokens[] = [
'type' => self::T_UNKNOWN,
'pos' => key($chars),
'value' => $current
];
next($chars);
continue;
}
$state = self::$transitionTable[$current];
if ($state === self::STATE_SINGLE_CHAR) {
// Consume simple tokens like ".", ",", "@", etc.
$tokens[] = [
'type' => $this->simpleTokens[$current],
'pos' => key($chars),
'value' => $current
];
next($chars);
} elseif ($state === self::STATE_IDENTIFIER) {
// Consume identifiers
$start = key($chars);
$buffer = '';
do {
$buffer .= $current;
$current = next($chars);
} while ($current !== false && isset($this->validIdentifier[$current]));
$tokens[] = [
'type' => self::T_IDENTIFIER,
'value' => $buffer,
'pos' => $start
];
} elseif ($state === self::STATE_WHITESPACE) {
// Skip whitespace
next($chars);
} elseif ($state === self::STATE_LBRACKET) {
// Consume "[", "[?", and "[]"
$position = key($chars);
$actual = next($chars);
if ($actual === ']') {
next($chars);
$tokens[] = [
'type' => self::T_FLATTEN,
'pos' => $position,
'value' => '[]'
];
} elseif ($actual === '?') {
next($chars);
$tokens[] = [
'type' => self::T_FILTER,
'pos' => $position,
'value' => '[?'
];
} else {
$tokens[] = [
'type' => self::T_LBRACKET,
'pos' => $position,
'value' => '['
];
}
} elseif ($state === self::STATE_STRING_LITERAL) {
// Consume raw string literals
$t = $this->inside($chars, "'", self::T_LITERAL);
$t['value'] = str_replace("\\'", "'", $t['value']);
$tokens[] = $t;
} elseif ($state === self::STATE_PIPE) {
// Consume pipe and OR
$tokens[] = $this->matchOr($chars, '|', '|', self::T_OR, self::T_PIPE);
} elseif ($state == self::STATE_JSON_LITERAL) {
// Consume JSON literals
$token = $this->inside($chars, '`', self::T_LITERAL);
if ($token['type'] === self::T_LITERAL) {
$token['value'] = str_replace('\\`', '`', $token['value']);
$token = $this->parseJson($token);
}
$tokens[] = $token;
} elseif ($state == self::STATE_NUMBER) {
// Consume numbers
$start = key($chars);
$buffer = '';
do {
$buffer .= $current;
$current = next($chars);
} while ($current !== false && isset($this->numbers[$current]));
$tokens[] = [
'type' => self::T_NUMBER,
'value' => (int)$buffer,
'pos' => $start
];
} elseif ($state === self::STATE_QUOTED_STRING) {
// Consume quoted identifiers
$token = $this->inside($chars, '"', self::T_QUOTED_IDENTIFIER);
if ($token['type'] === self::T_QUOTED_IDENTIFIER) {
$token['value'] = '"' . $token['value'] . '"';
$token = $this->parseJson($token);
}
$tokens[] = $token;
} elseif ($state === self::STATE_EQ) {
// Consume equals
$tokens[] = $this->matchOr($chars, '=', '=', self::T_COMPARATOR, self::T_UNKNOWN);
} elseif ($state == self::STATE_AND) {
$tokens[] = $this->matchOr($chars, '&', '&', self::T_AND, self::T_EXPREF);
} elseif ($state === self::STATE_NOT) {
// Consume not equal
$tokens[] = $this->matchOr($chars, '!', '=', self::T_COMPARATOR, self::T_NOT);
} else {
// either '<' or '>'
// Consume less than and greater than
$tokens[] = $this->matchOr($chars, $current, '=', self::T_COMPARATOR, self::T_COMPARATOR);
}
}
eof:
$tokens[] = [
'type' => self::T_EOF,
'pos' => strlen($input),
'value' => null
];
return $tokens;
}
/**
* Returns a token based on whether or not the next token matches the
* expected value. If it does, a token of "$type" is returned. Otherwise,
* a token of "$orElse" type is returned.
*
* @param array $chars Array of characters by reference.
* @param string $current The current character.
* @param string $expected Expected character.
* @param string $type Expected result type.
* @param string $orElse Otherwise return a token of this type.
*
* @return array Returns a conditional token.
*/
private function matchOr(array &$chars, $current, $expected, $type, $orElse)
{
if (next($chars) === $expected) {
next($chars);
return [
'type' => $type,
'pos' => key($chars) - 1,
'value' => $current . $expected
];
}
return [
'type' => $orElse,
'pos' => key($chars) - 1,
'value' => $current
];
}
/**
* Returns a token the is the result of consuming inside of delimiter
* characters. Escaped delimiters will be adjusted before returning a
* value. If the token is not closed, "unknown" is returned.
*
* @param array $chars Array of characters by reference.
* @param string $delim The delimiter character.
* @param string $type Token type.
*
* @return array Returns the consumed token.
*/
private function inside(array &$chars, $delim, $type)
{
$position = key($chars);
$current = next($chars);
$buffer = '';
while ($current !== $delim) {
if ($current === '\\') {
$buffer .= '\\';
$current = next($chars);
}
if ($current === false) {
// Unclosed delimiter
return [
'type' => self::T_UNKNOWN,
'value' => $buffer,
'pos' => $position
];
}
$buffer .= $current;
$current = next($chars);
}
next($chars);
return ['type' => $type, 'value' => $buffer, 'pos' => $position];
}
/**
* Parses a JSON token or sets the token type to "unknown" on error.
*
* @param array $token Token that needs parsing.
*
* @return array Returns a token with a parsed value.
*/
private function parseJson(array $token)
{
$value = json_decode($token['value'], true);
if ($error = json_last_error()) {
// Legacy support for elided quotes. Try to parse again by adding
// quotes around the bad input value.
$value = json_decode('"' . $token['value'] . '"', true);
if ($error = json_last_error()) {
$token['type'] = self::T_UNKNOWN;
return $token;
}
}
$token['value'] = $value;
return $token;
}
}
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