Merge: Bytes from hexdigest

[nit.git] / lib / core / bytes.nit

diff --git a/lib/core/bytes.nit b/lib/core/bytes.nit
index d589646..356f386 100644 (file)
--- a/lib/core/bytes.nit
+++ b/lib/core/bytes.nit
@@ -27,6 +27,51 @@ redef class Byte
                tmp = 0x0Fu8 & self
                ns[pos + 1] = if tmp >= 0x0Au8 then tmp + 0x37u8 else tmp + 0x30u8
        end
+
+       # Is `self` a valid hexadecimal digit (in ASCII)
+       #
+       # ~~~nit
+       # intrude import core::bytes
+       # assert not '/'.ascii.to_b.is_valid_hexdigit
+       # assert '0'.ascii.to_b.is_valid_hexdigit
+       # assert '9'.ascii.to_b.is_valid_hexdigit
+       # assert not ':'.ascii.to_b.is_valid_hexdigit
+       # assert not '@'.ascii.to_b.is_valid_hexdigit
+       # assert 'A'.ascii.to_b.is_valid_hexdigit
+       # assert 'F'.ascii.to_b.is_valid_hexdigit
+       # assert not 'G'.ascii.to_b.is_valid_hexdigit
+       # assert not '`'.ascii.to_b.is_valid_hexdigit
+       # assert 'a'.ascii.to_b.is_valid_hexdigit
+       # assert 'f'.ascii.to_b.is_valid_hexdigit
+       # assert not 'g'.ascii.to_b.is_valid_hexdigit
+       # ~~~
+       private fun is_valid_hexdigit: Bool do
+               return (self >= 0x30u8 and self <= 0x39u8) or
+                      (self >= 0x41u8 and self <= 0x46u8) or
+                      (self >= 0x61u8 and self <= 0x66u8)
+       end
+
+       # `self` as a hexdigit to its byte value
+       #
+       # ~~~nit
+       # intrude import core::bytes
+       # assert 0x39u8.hexdigit_to_byteval == 0x09u8
+       # assert 0x43u8.hexdigit_to_byteval == 0x0Cu8
+       # ~~~
+       #
+       # REQUIRE: `self.is_valid_hexdigit`
+       private fun hexdigit_to_byteval: Byte do
+               if self >= 0x30u8 and self <= 0x39u8 then
+                       return self - 0x30u8
+               else if self >= 0x41u8 and self <= 0x46u8 then
+                       return self - 0x37u8
+               else if self >= 0x61u8 and self <= 0x66u8 then
+                       return self - 0x57u8
+               end
+               # Happens only if the requirement is not met.
+               # i.e. this abort is here to please the compiler
+               abort
+       end
 end
 
 # A buffer containing Byte-manipulation facilities
@@ -188,7 +233,7 @@ private class BytesIterator
 
        var max: Int
 
-       init with_buffer(b: Bytes) do init(b.items, 0, b.length - 1)
+       init with_buffer(b: Bytes) do init(b.items, 0, b.length)
 
        redef fun is_ok do return index < max
 
@@ -210,6 +255,15 @@ redef class Text
                return b
        end
 
+       # Is `self` a valid hexdigest ?
+       #
+       #     assert "0B1d3F".is_valid_hexdigest
+       #     assert not "5G".is_valid_hexdigest
+       fun is_valid_hexdigest: Bool do
+               for i in bytes do if not i.is_valid_hexdigit then return false
+               return true
+       end
+
        # Appends `self.bytes` to `b`
        fun append_to_bytes(b: Bytes) do
                for s in substrings do
@@ -217,6 +271,24 @@ redef class Text
                        b.append_ns_from(s.items, s.bytelen, from)
                end
        end
+
+       # Returns a new `Bytes` instance with the digest as content
+       #
+       #     assert "0B1F4D".hexdigest_to_bytes == [0x0Bu8, 0x1Fu8, 0x4Du8]
+       #
+       # REQUIRE: `self` is a valid hexdigest and hexdigest.length % 2 == 0
+       fun hexdigest_to_bytes: Bytes do
+               var b = bytes
+               var pos = 0
+               var max = bytelen
+               var ret = new Bytes.with_capacity(max / 2)
+               while pos < max do
+                       ret.add((b[pos].hexdigit_to_byteval << 4) |
+                       b[pos + 1].hexdigit_to_byteval)
+                       pos += 2
+               end
+               return ret
+       end
 end
 
 redef class FlatText