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// Ruler is helper class to build responsibility chains from parse rules.
// It allows:
//
// - easy stack rules chains
// - getting main chain and named chains content (as arrays of functions)
//
'use strict';
////////////////////////////////////////////////////////////////////////////////
function Ruler() {
// List of added rules. Each element is:
//
// {
// name: XXX,
// enabled: Boolean,
// fn: Function(),
// alt: [ name2, name3 ]
// }
//
this.__rules__ = [];
// Cached rule chains.
//
// First level - chain name, '' for default.
// Second level - diginal anchor for fast filtering by charcodes.
//
this.__cache__ = null;
}
////////////////////////////////////////////////////////////////////////////////
// Helper methods, should not be used directly
// Find rule index by name
//
Ruler.prototype.__find__ = function (name) {
for (var i = 0; i < this.__rules__.length; i++) {
if (this.__rules__[i].name === name) {
return i;
}
}
return -1;
};
// Build rules lookup cache
//
Ruler.prototype.__compile__ = function () {
var self = this;
var chains = [ '' ];
// collect unique names
self.__rules__.forEach(function (rule) {
if (!rule.enabled) { return; }
rule.alt.forEach(function (altName) {
if (chains.indexOf(altName) < 0) {
chains.push(altName);
}
});
});
self.__cache__ = {};
chains.forEach(function (chain) {
self.__cache__[chain] = [];
self.__rules__.forEach(function (rule) {
if (!rule.enabled) { return; }
if (chain && rule.alt.indexOf(chain) < 0) { return; }
self.__cache__[chain].push(rule.fn);
});
});
};
////////////////////////////////////////////////////////////////////////////////
// Public methods
// Replace rule function
//
Ruler.prototype.at = function (name, fn, options) {
var index = this.__find__(name);
var opt = options || {};
if (index === -1) { throw new Error('Parser rule not found: ' + name); }
this.__rules__[index].fn = fn;
this.__rules__[index].alt = opt.alt || [];
this.__cache__ = null;
};
// Add rule to chain before one with given name.
//
Ruler.prototype.before = function (beforeName, ruleName, fn, options) {
var index = this.__find__(beforeName);
var opt = options || {};
if (index === -1) { throw new Error('Parser rule not found: ' + beforeName); }
this.__rules__.splice(index, 0, {
name: ruleName,
enabled: true,
fn: fn,
alt: opt.alt || []
});
this.__cache__ = null;
};
// Add rule to chain after one with given name.
//
Ruler.prototype.after = function (afterName, ruleName, fn, options) {
var index = this.__find__(afterName);
var opt = options || {};
if (index === -1) { throw new Error('Parser rule not found: ' + afterName); }
this.__rules__.splice(index + 1, 0, {
name: ruleName,
enabled: true,
fn: fn,
alt: opt.alt || []
});
this.__cache__ = null;
};
// Add rule to the end of chain.
//
Ruler.prototype.push = function (ruleName, fn, options) {
var opt = options || {};
this.__rules__.push({
name: ruleName,
enabled: true,
fn: fn,
alt: opt.alt || []
});
this.__cache__ = null;
};
// Enable rules by names.
//
Ruler.prototype.enable = function (list, ignoreInvalid) {
if (!Array.isArray(list)) { list = [ list ]; }
// Search by name and enable
list.forEach(function (name) {
var idx = this.__find__(name);
if (idx < 0) {
if (ignoreInvalid) { return; }
throw new Error('Rules manager: invalid rule name ' + name);
}
this.__rules__[idx].enabled = true;
}, this);
this.__cache__ = null;
};
// Enable rules by whitelisted names (others will be disables).
//
Ruler.prototype.enableOnly = function (list, ignoreInvalid) {
if (!Array.isArray(list)) { list = [ list ]; }
this.__rules__.forEach(function (rule) { rule.enabled = false; });
this.enable(list, ignoreInvalid);
};
// Disable rules by names.
//
Ruler.prototype.disable = function (list, ignoreInvalid) {
if (!Array.isArray(list)) {
list = [ list ];
}
// Search by name and disable
list.forEach(function (name) {
var idx = this.__find__(name);
if (idx < 0) {
if (ignoreInvalid) { return; }
throw new Error('Rules manager: invalid rule name ' + name);
}
this.__rules__[idx].enabled = false;
}, this);
this.__cache__ = null;
};
// Get rules list as array of functions.
//
Ruler.prototype.getRules = function (chainName) {
if (this.__cache__ === null) {
this.__compile__();
}
// Chain can be empty, if rules disabled. But we still have to return Array.
return this.__cache__[chainName] || [];
};
module.exports = Ruler;