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var hpack = require('../hpack');
var utils = hpack.utils;
var assert = utils.assert;
function Table(options) {
this['static'] = hpack['static-table'];
this.dynamic = [];
this.size = 0;
this.maxSize = 0;
this.length = this['static'].table.length;
this.protocolMaxSize = options.maxSize;
this.maxSize = this.protocolMaxSize;
this.lookupDepth = options.lookupDepth || 32;
}
module.exports = Table;
Table.create = function create(options) {
return new Table(options);
};
Table.prototype.lookup = function lookup(index) {
assert(index !== 0, 'Zero indexed field');
assert(index <= this.length, 'Indexed field OOB')
if (index <= this['static'].table.length)
return this['static'].table[index - 1];
else
return this.dynamic[this.length - index];
};
Table.prototype.reverseLookup = function reverseLookup(name, value) {
var staticEntry = this['static'].map[name];
if (staticEntry && staticEntry.values[value])
return staticEntry.values[value];
// Reverse search dynamic table (new items are at the end of it)
var limit = Math.max(0, this.dynamic.length - this.lookupDepth);
for (var i = this.dynamic.length - 1; i >= limit; i--) {
var entry = this.dynamic[i];
if (entry.name === name && entry.value === value)
return this.length - i;
if (entry.name === name) {
// Prefer smaller index
if (staticEntry)
break;
return -(this.length - i);
}
}
if (staticEntry)
return -staticEntry.index;
return 0;
};
Table.prototype.add = function add(name, value, nameSize, valueSize) {
var totalSize = nameSize + valueSize + 32;
this.dynamic.push({
name: name,
value: value,
nameSize: nameSize,
totalSize: totalSize
});
this.size += totalSize;
this.length++;
this.evict();
};
Table.prototype.evict = function evict() {
while (this.size > this.maxSize) {
var entry = this.dynamic.shift();
this.size -= entry.totalSize;
this.length--;
}
assert(this.size >= 0, 'Table size sanity check failed');
};
Table.prototype.updateSize = function updateSize(size) {
assert(size <= this.protocolMaxSize, 'Table size bigger than maximum');
this.maxSize = size;
this.evict();
};