%PDF-
%PDF-
Mini Shell
Mini Shell
'use strict'
const {
wellknownHeaderNames,
headerNameLowerCasedRecord
} = require('./constants')
class TstNode {
/** @type {any} */
value = null
/** @type {null | TstNode} */
left = null
/** @type {null | TstNode} */
middle = null
/** @type {null | TstNode} */
right = null
/** @type {number} */
code
/**
* @param {Uint8Array} key
* @param {any} value
* @param {number} index
*/
constructor (key, value, index) {
if (index === undefined || index >= key.length) {
throw new TypeError('Unreachable')
}
this.code = key[index]
if (key.length !== ++index) {
this.middle = new TstNode(key, value, index)
} else {
this.value = value
}
}
/**
* @param {Uint8Array} key
* @param {any} value
* @param {number} index
*/
add (key, value, index) {
if (index === undefined || index >= key.length) {
throw new TypeError('Unreachable')
}
const code = key[index]
if (this.code === code) {
if (key.length === ++index) {
this.value = value
} else if (this.middle !== null) {
this.middle.add(key, value, index)
} else {
this.middle = new TstNode(key, value, index)
}
} else if (this.code < code) {
if (this.left !== null) {
this.left.add(key, value, index)
} else {
this.left = new TstNode(key, value, index)
}
} else if (this.right !== null) {
this.right.add(key, value, index)
} else {
this.right = new TstNode(key, value, index)
}
}
/**
* @param {Uint8Array} key
* @return {TstNode | null}
*/
search (key) {
const keylength = key.length
let index = 0
let node = this
while (node !== null && index < keylength) {
let code = key[index]
// A-Z
if (code >= 0x41 && code <= 0x5a) {
// Lowercase for uppercase.
code |= 32
}
while (node !== null) {
if (code === node.code) {
if (keylength === ++index) {
// Returns Node since it is the last key.
return node
}
node = node.middle
break
}
node = node.code < code ? node.left : node.right
}
}
return null
}
}
class TernarySearchTree {
/** @type {TstNode | null} */
node = null
/**
* @param {Uint8Array} key
* @param {any} value
* */
insert (key, value) {
if (this.node === null) {
this.node = new TstNode(key, value, 0)
} else {
this.node.add(key, value, 0)
}
}
/**
* @param {Uint8Array} key
*/
lookup (key) {
return this.node?.search(key)?.value ?? null
}
}
const tree = new TernarySearchTree()
for (let i = 0; i < wellknownHeaderNames.length; ++i) {
const key = headerNameLowerCasedRecord[wellknownHeaderNames[i]]
tree.insert(Buffer.from(key), key)
}
module.exports = {
TernarySearchTree,
tree
}
Zerion Mini Shell 1.0