urbit-ob

commit cdb6ca8fdb227112f59d12c6163b8b8910785a00
parent b1fd6f53459701fe310c3be0d738d3ee417e6d01
Author: Jared Tobin <jared@jtobin.io>
Date:   Sat, 10 Nov 2018 19:09:30 +1300

Preserve leading zeros in patq2hex/hex2patq.

Ensures that we don't chop off leading zeros when converting between
representations.  Even though the resulting @q values are considered
equal, the behaviour can make string manipulation annoying.

Diffstat:
M
src/internal/co.js
 | 
65
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
M
test/co.test.js
 | 
6
+++---

2 files changed, 60 insertions(+), 11 deletions(-)
diff --git a/src/internal/co.js b/src/internal/co.js
@@ -126,6 +126,15 @@ const hex2patp = (hex) =>
   patp(new BN(hex, 'hex'))
 
 /**
+ * Convert a Buffer to a @p-encoded string.
+ *
+ * @param  {Buffer}  buf
+ * @return  {String}
+ */
+const buf2patp = (buf) =>
+  hex2patp(buf.toString('hex'))
+
+/**
  * Convert a @p-encoded string to a hex-encoded string.
  *
  * @param  {String}  name @p
@@ -147,10 +156,22 @@ const patp2hex = (name) => {
   '')
 
   const bn = new BN(addr, 2)
-  return ob.fend(bn).toString('hex')
+  const hex = ob.fend(bn).toString('hex')
+  return hex.length % 2 !== 0
+    ? hex.padStart(hex.length + 1, '0')
+    : hex
 }
 
 /**
+ * Convert a @p-encoded string to a Buffer.
+ *
+ * @param  {String}  name
+ * @return  {Buffer}
+ */
+const patp2buf = name =>
+  Buffer.from(patp2hex(name), 'hex')
+
+/**
  * Convert a @p-encoded string to a bignum.
  *
  * @param  {String}  name @p
@@ -175,10 +196,18 @@ const patp2dec = name =>
  * @return  {String}
  */
 const patq = (arg) => {
-  const n = new BN(arg)
-
-  const buf = n.toArrayLike(Buffer)
+  const bn = new BN(arg)
+  const buf = bn.toArrayLike(Buffer)
+  return buf2patq(buf)
+}
 
+/**
+ * Convert a Buffer into a @q-encoded string.
+ *
+ * @param  {Buffer}  buf
+ * @return  {String}
+ */
+const buf2patq = buf => {
   const chunked =
     buf.length % 2 !== 0 && buf.length > 1
     ? lodash.concat([[buf[0]]], lodash.chunk(buf.slice(1), 2))
@@ -206,11 +235,20 @@ const patq = (arg) => {
 /**
  * Convert a hex-encoded string to a @q-encoded string.
  *
+ * Note that this preserves leading zero bytes.
+ *
  * @param  {String}  hex
  * @return  {String}
  */
-const hex2patq = hex =>
-  patq(new BN(hex, 'hex'))
+const hex2patq = arg => {
+  const hex =
+    arg.length % 2 !== 0
+    ? arg.padStart(arg.length + 1, '0')
+    : arg
+
+  const buf = Buffer.from(hex, 'hex')
+  return buf2patq(buf)
+}
 
 /**
  * Convert a @q-encoded string to a hex-encoded string.
@@ -251,6 +289,17 @@ const patq2bn = name =>
   new BN(patq2hex(name), 'hex')
 
 /**
+ * Convert a @q-encoded string to a Buffer.
+ *
+ * @param  {String}  name @q
+ * @return  {Buffer}
+ */
+const patq2buf = name => {
+  const hex = patq2hex(name)
+  return Buffer.from(hex, 'hex')
+}
+
+/**
  * Convert a @q-encoded string to a decimal-encoded string.
  *
  * @param  {String}  name @q
@@ -362,12 +411,12 @@ const eqPatq = (p, q) => {
 module.exports = {
   patp,
   patp2hex,
-  patp2dec,
   hex2patp,
+  patp2dec,
   patq,
   patq2hex,
-  patq2dec,
   hex2patq,
+  patq2dec,
   clan,
   sein,
   eqPatq
diff --git a/test/co.test.js b/test/co.test.js
@@ -1,15 +1,15 @@
 const BN = require('bn.js')
-const { expect } = require('chai');
+const { expect } = require('chai')
 const jsc = require('jsverify')
 const {
   patp,
   patp2hex,
-  patp2dec,
   hex2patp,
+  patp2dec,
   patq,
   patq2hex,
-  patq2dec,
   hex2patq,
+  patq2dec,
   clan,
   sein,
   eqPatq