lib/QueryParser.js
const XRegExp = require('xregexp');
const Helpers = require('./Helpers');
// --------------------------------------------------------------------------
/**
* Internal object for parsing query fragments
*
* @private
* @param {Driver} driver - The driver object for the database in use
*/
class QueryParser {
/**
* @constructor
*
* @param {Driver} driver - The driver object for the database in use
* @return {void}
*/
constructor (driver) {
this.driver = driver;
const matchPatterns = {
function: /([a-z0-9_]+\((.*)\))/i,
operator: /!=?|=|\+|&&?|~|\|\|?|\^|\/|<>|>=?|<=?|-|%|OR|AND|NOT|XOR/ig,
literal: /([0-9]+)|'(.*?)'|true|false/ig
};
// Full pattern for identifiers
// Making sure that literals and functions aren't matched
matchPatterns.identifier = XRegExp(
`(
(?!
${matchPatterns['function'].source}|
${matchPatterns.literal.source}
)
([a-z_-]+[0-9]*\\.?)
)+`, 'igx');
// Full pattern for determining ordering of the pieces
matchPatterns.joinCombined = XRegExp(
`${matchPatterns['function'].source}+| # functions
${matchPatterns.literal.source}+| # literal values
${matchPatterns.identifier.source} # identifiers
|(${matchPatterns.operator.source})+`, 'igx');
this.matchPatterns = matchPatterns;
this.identifierBlacklist = ['true', 'false', 'null'];
}
/**
* Filter matched patterns
*
* @param {Array} array - Set of possible matches
* @return {Array|null} - Filtered set of possible matches
*/
filterMatches (array) {
const output = [];
// Return non-array matches
if (Helpers.isNull(array)) {
return null;
}
array.forEach(item => {
output.push(item);
});
return output;
}
/**
* Check if the string contains an operator, and if so, return the operator(s).
* If there are no matches, return null
*
* @param {String} string - the string to check
* @return {Array|null} - List of operators
*/
hasOperator (string) {
return this.filterMatches(string.match(this.matchPatterns.operator));
}
/**
* Tokenize the sql into parts for additional processing
*
* @param {String} sql - Join sql to parse
* @return {Object} - Join condition components
*/
parseJoin (sql) {
const matches = {};
const output = {
functions: [],
identifiers: [],
operators: [],
literals: []
};
// Get clause components
matches.functions = sql.match(new RegExp(this.matchPatterns['function'].source, 'ig'));
matches.identifiers = sql.match(this.matchPatterns.identifier);
matches.operators = sql.match(this.matchPatterns.operator);
matches.literals = sql.match(this.matchPatterns.literal);
// Get everything at once for ordering
matches.combined = sql.match(this.matchPatterns.joinCombined);
// Flatten the matches to increase relevance
Object.keys(matches).forEach(key => {
output[key] = this.filterMatches(matches[key]);
});
return output;
}
/**
* Return the output of the parsing of the join condition
*
* @param {String} condition - The join condition to evaluate
* @return {String} - The parsed/escaped join condition
*/
compileJoin (condition) {
const parts = this.parseJoin(condition);
// Quote the identifiers
parts.combined.forEach((part, i) => {
if (parts.identifiers.indexOf(part) !== -1 && !Helpers.isNumber(part)) {
parts.combined[i] = this.driver.quoteIdentifiers(part);
}
});
return parts.combined.join(' ');
}
/**
* Parse a where clause to separate functions from values
*
* @param {Driver} driver - The current db driver
* @param {State} state - Query Builder state object
* @return {String} - The parsed/escaped where condition
*/
parseWhere (driver, state) {
const whereMap = state.whereMap;
let whereValues = state.rawWhereValues;
const outputMap = [];
const outputValues = [];
Object.keys(whereMap).forEach(key => {
// Combine fields, operators, functions and values into a full clause
// to have a common starting flow
let fullClause = '';
// Add an explicit = sign where one is inferred
if (!this.hasOperator(key)) {
fullClause = `${key} = ${whereMap[key]}`;
} else if (whereMap[key] === key) {
fullClause = key;
} else {
fullClause = `${key} ${whereMap[key]}`;
}
// Separate the clause into separate pieces
const parts = this.parseJoin(fullClause);
// Filter explicit literals from lists of matches
if (whereValues.indexOf(whereMap[key]) !== -1) {
const value = whereMap[key];
const identIndex = parts.identifiers.indexOf(value);
const litIndex = (Helpers.isArray(parts.literals)) ? parts.literals.indexOf(value) : -1;
const combIndex = parts.combined.indexOf(value);
const funcIndex = (Helpers.isArray(parts.functions)) ? parts.functions.indexOf(value) : -1;
let inOutputArray = outputValues.includes(value);
// Remove the identifier in question,
// and add to the output values array
if (identIndex !== -1) {
parts.identifiers.splice(identIndex, 1);
if (!inOutputArray) {
outputValues.push(value);
inOutputArray = true;
}
}
// Remove the value from the literals list
// so it is not added twice
if (litIndex !== -1) {
parts.literals.splice(litIndex, 1);
if (!inOutputArray) {
outputValues.push(value);
inOutputArray = true;
}
}
// Remove the value from the combined list
// and replace it with a placeholder
if (combIndex !== -1 && funcIndex === -1) {
// Make sure to skip functions when replacing values
parts.combined[combIndex] = '?';
}
}
// Filter false positive identifiers
parts.identifiers = parts.identifiers.filter(item => {
const isInCombinedMatches = parts.combined.indexOf(item) !== -1;
const isNotInBlackList = this.identifierBlacklist.indexOf(item.toLowerCase()) === -1;
return isInCombinedMatches && isNotInBlackList;
}, this);
// Quote identifiers
if (Helpers.isArray(parts.identifiers)) {
parts.identifiers.forEach(ident => {
const index = parts.combined.indexOf(ident);
if (index !== -1) {
parts.combined[index] = driver.quoteIdentifiers(ident);
}
});
}
// Replace each literal with a placeholder in the map
// and add the literal to the values,
// This should only apply to literal values that are not
// explicitly mapped to values, but have to be parsed from
// a where condition,
if (Helpers.isArray(parts.literals)) {
parts.literals.forEach(lit => {
const litIndex = parts.combined.indexOf(lit);
if (litIndex !== -1) {
parts.combined[litIndex] = '?';
outputValues.push(lit);
}
});
}
outputMap.push(parts.combined.join(' '));
});
state.rawWhereValues = [];
state.whereValues = state.whereValues.concat(outputValues);
state.whereMap = outputMap;
return state;
}
}
module.exports = QueryParser;