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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';
////////////////////////////////////////////////////////////////////////////////
// helpers
function _class(obj) { return Object.prototype.toString.call(obj); }
function isFunction(obj) { return _class(obj) === '[object Function]'; }
function functionName(fn) {
var ret = fn.toString();
ret = ret.substr('function '.length);
ret = ret.substr(0, ret.indexOf('('));
return ret;
}
////////////////////////////////////////////////////////////////////////////////
function Ruler(compileFn) {
this.compile = compileFn; // callback to call after each change
// List of added rules. Each element is:
//
// {
// name: XXX,
// enabled: Boolean,
// fn: Function(),
// alt: [ name2, name3 ]
// }
//
this.rules = [];
}
// 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;
};
// Replace/delete parser function
//
Ruler.prototype.at = function (name, fn, altNames) {
var index = this.find(name);
if (index === -1) {
throw new Error('Parser rule not found: ' + name);
}
if (isFunction(fn)) {
this.rules[index].fn = fn;
if (altNames) {
this.rules[index].alt = altNames;
}
} else {
this.rules = this.rules.slice(0, index).concat(this.rules.slice(index + 1));
}
this.compile();
};
// Add function to parser chain before one with given name.
// Or add to start, if name not defined
//
Ruler.prototype.before = function (name, fn, altNames) {
var index, rule;
if (isFunction(name)) {
altNames = fn;
fn = name;
name = '';
}
rule = {
name: functionName(fn),
enabled: true,
fn: fn,
alt: altNames || []
};
if (!name) {
this.rules.unshift(rule);
} else {
index = this.find(name);
if (index === -1) {
throw new Error('Parser rule not found: ' + name);
}
this.rules.splice(index, 0, rule);
}
this.compile();
};
// Add function to parser chain after one with given name.
// Or add to end, if name not defined
//
Ruler.prototype.after = function (name, fn, altNames) {
var index, rule;
if (isFunction(name)) {
altNames = fn;
fn = name;
name = '';
}
rule = {
name: functionName(fn),
enabled: true,
fn: fn,
alt: altNames || []
};
if (!name) {
this.rules.push(rule);
} else {
index = this.find(name);
if (index === -1) {
throw new Error('Parser rule not found: ' + name);
}
this.rules.splice(index + 1, 0, rule);
}
this.compile();
};
// Get rules list as array of functions. By default returns main chain
//
Ruler.prototype.getRules = function (chainName) {
var result = [];
if (!chainName) {
this.rules.forEach(function (rule) {
if (rule.enabled) {
result.push(rule.fn);
}
});
return result;
}
this.rules.forEach(function (rule) {
if (rule.alt.indexOf(chainName) >= 0 && rule.enabled) {
result.push(rule.fn);
}
});
return result;
};
// Enable list of rules by names. If `strict` is true, then all non listed
// rules will be disabled.
//
Ruler.prototype.enable = function (list, strict) {
if (!Array.isArray(list)) {
list = [ list ];
}
// In strict mode disable all existing rules first
if (strict) {
this.rules.forEach(function (rule) {
rule.enabled = false;
});
}
// Search by name and enable
list.forEach(function (name) {
var idx = this.find(name);
if (idx < 0) { throw new Error('Rules manager: invalid rule name ' + name); }
this.rules[idx].enabled = true;
}, this);
this.compile();
};
// Disable list of rules by names.
//
Ruler.prototype.disable = function (list) {
if (!Array.isArray(list)) {
list = [ list ];
}
// Search by name and disable
list.forEach(function (name) {
var idx = this.find(name);
if (idx < 0) { throw new Error('Rules manager: invalid rule name ' + name); }
this.rules[idx].enabled = false;
}, this);
this.compile();
};
module.exports = Ruler;