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TiddlyWiki5/core/modules/indexers/field-indexer.js

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/*\
title: $:/core/modules/indexers/field-indexer.js
type: application/javascript
module-type: indexer
Indexes the tiddlers with each field value
\*/
(function(){
/*jslint node: true, browser: true */
/*global modules: false */
"use strict";
var DEFAULT_MAXIMUM_INDEXED_VALUE_LENGTH = 128;
function FieldIndexer(wiki) {
this.wiki = wiki;
}
FieldIndexer.prototype.init = function() {
this.index = null;
this.maxIndexedValueLength = DEFAULT_MAXIMUM_INDEXED_VALUE_LENGTH;
this.addIndexMethods();
}
// Provided for testing
FieldIndexer.prototype.setMaxIndexedValueLength = function(length) {
this.index = null;
this.maxIndexedValueLength = length;
};
FieldIndexer.prototype.addIndexMethods = function() {
var self = this;
// get all tiddlers, including those overwrite shadow tiddlers
this.wiki.each.byField = function(name,value) {
var lookup = self.lookup(name,value);
return lookup && lookup.filter(function(title) {
return self.wiki.tiddlerExists(title)
});
};
// get shadow tiddlers, including shadow tiddlers that is overwritten
this.wiki.eachShadow.byField = function(name,value) {
var lookup = self.lookup(name,value);
return lookup && lookup.filter(function(title) {
return self.wiki.isShadowTiddler(title)
});
};
this.wiki.eachTiddlerPlusShadows.byField = function(name,value) {
var lookup = self.lookup(name,value);
return lookup ? lookup.slice(0) : null;
};
this.wiki.eachShadowPlusTiddlers.byField = function(name,value) {
var lookup = self.lookup(name,value);
return lookup ? lookup.slice(0) : null;
};
};
/*
Tear down and then rebuild the index as if all tiddlers have changed
*/
FieldIndexer.prototype.rebuild = function() {
// Invalidate the index so that it will be rebuilt when it is next used
this.index = null;
};
/*
Build the index for a particular field
*/
FieldIndexer.prototype.buildIndexForField = function(name) {
var self = this;
// Hashmap by field name of hashmap by field value of array of tiddler titles
this.index = this.index || Object.create(null);
this.index[name] = Object.create(null);
var baseIndex = this.index[name];
// Update the index for each tiddler
this.wiki.eachTiddlerPlusShadows(function(tiddler,title) {
if(name in tiddler.fields) {
var value = tiddler.getFieldString(name);
// Skip any values above the maximum length
if(value.length < self.maxIndexedValueLength) {
baseIndex[value] = baseIndex[value] || [];
baseIndex[value].push(title);
}
}
});
};
/*
Update the index in the light of a tiddler value changing; note that the title must be identical. (Renames are handled as a separate delete and create)
updateDescriptor: {old: {tiddler: <tiddler>, shadow: <boolean>, exists: <boolean>},new: {tiddler: <tiddler>, shadow: <boolean>, exists: <boolean>}}
*/
FieldIndexer.prototype.update = function(updateDescriptor) {
var self = this;
// Don't do anything if the index hasn't been built yet
if(this.index === null) {
return;
}
// Remove the old tiddler from the index
if(updateDescriptor.old.tiddler) {
$tw.utils.each(this.index,function(indexEntry,name) {
if(name in updateDescriptor.old.tiddler.fields) {
var value = updateDescriptor.old.tiddler.getFieldString(name),
tiddlerList = indexEntry[value];
if(tiddlerList) {
var index = tiddlerList.indexOf(updateDescriptor.old.tiddler.fields.title);
if(index !== -1) {
tiddlerList.splice(index,1);
}
}
}
});
}
// Add the new tiddler to the index
if(updateDescriptor["new"].tiddler) {
$tw.utils.each(this.index,function(indexEntry,name) {
if(name in updateDescriptor["new"].tiddler.fields) {
var value = updateDescriptor["new"].tiddler.getFieldString(name);
if(value.length < self.maxIndexedValueLength) {
indexEntry[value] = indexEntry[value] || [];
indexEntry[value].push(updateDescriptor["new"].tiddler.fields.title);
}
}
});
}
};
// Lookup the given field returning a list of tiddler titles
FieldIndexer.prototype.lookup = function(name,value) {
// Fail the lookup if the value is too long
if(value.length >= this.maxIndexedValueLength) {
return null;
}
// Update the index if it has yet to be built
if(this.index === null || !this.index[name]) {
this.buildIndexForField(name);
}
return this.index[name][value] || [];
};
exports.FieldIndexer = FieldIndexer;
})();