wharfdb.stringfact-codec

Encode stringfacts into sortable keys. Decode keys. Make a matcher (partial encoder) to search through keys.

Example

var encode      = require("wharfdb.stringfact-codec/encode");
var decode      = require("wharfdb.stringfact-codec/decode");
var makeMatcher = require("wharfdb.stringfact-codec/makeMatcher");
 
var key = encode("avtoe", {
  e: "12345",
  a: ":user/name",
  v: "Bob",
  t: "txn0001",
  o: "1"
});
var m = makeMatcher("avtoe", {
  a: ":user/name",
  v: "Bob"
});
 
console.log("key", key);
console.log("decode", decode(key));
console.log("m.prefix", m.prefix);
console.log("m.match(key)", m.match(key));

Here's the output:

key "avtoe|:user/name|Bob|txn0001|1|12345"
decode ["avtoe", {a: ":user/name", v: "Bob", t: "txn0001", o: "1", e: "12345"}]
m.prefix "avtoe|:user/name|Bob|"
m.match(key) true

What is ...

stringfact

A WharfDB fact where all the values are strings. The strings may contain any characters they want and there is no limit on their length.

{
  e: "12345",
  a: ":user/name",
  v: "Bob",
  t: "txn0001",
  o: "1"
}

index

A string that defines the order in which the fact should be sorted. It's expected to be lowercase, no spaces and each character represents the part of the fact.

"eavto"
// - or -
"avtoe"

key

A string that is the encoded fact and index. This key can be stored into your sorted database.

"eavto|12345|:user/name|Bob|txn0001|1"

qStringfact

A partial stringfact where missing keys are considered unknown.

{
  //we know the attribute and value, but we don't know the rest.
  a: ":user/name",
  v: "Bob"
}

API

//Here are the main functions you'll need
var encode      = require("wharfdb.stringfact-codec/encode");
var decode      = require("wharfdb.stringfact-codec/decode");
var makeMatcher = require("wharfdb.stringfact-codec/makeMatcher");
 
//here are some things that might come in handy if you need advanced stuff.
var encodeValue = require("wharfdb.stringfact-codec/encodeValue");
var separator   = require("wharfdb.stringfact-codec/separator");
var escapper    = require("wharfdb.stringfact-codec/escapper");

encode(index, stringfact) -> key

Given an index and a stringfact return a key.

decode(key) -> [index, stringfact]

Given a key return an array with the decoded index and stringfact.

makeMatcher(index, qStringfact) -> {prefix: , matcher: }

Given an index and a qStringfact return an object with 2 properties:

• prefix - a string that is the prefix of the encoded qStringfact.
• matcher(key) -> t/f - a function that given a key will return true if it matches the qStringfact.

encodeValue(value) -> encoded_value

Given any string encode it escaping special characters.

separator

The character used to separate values in the key.

escapper

The character used for escaping things.

License

MIT