add a bytes package analogous to the strings package.

also has Equal and Compare

R=rsc
DELTA=348  (348 added, 0 deleted, 0 changed)
OCL=29892
CL=29894

1 files changed, 154 insertions, 0 deletions

diff --git a/src/lib/bytes/bytes.go b/src/lib/bytes/bytes.go
new file mode 100644
index 000000000..fe97b0495
--- /dev/null
+++ b/src/lib/bytes/bytes.go
@@ -0,0 +1,154 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// A package of simple functions to manipulate arrays of bytes.
+// Analagous to the facilities of the strings package.
+package bytes
+
+import "utf8"
+
+// Compare returns an integer comparing the two byte arrays lexicographically.
+// The result will be 0 if a==b, -1 if a < b, and +1 if a > b
+func Compare(a, b []byte) int {
+	for i := 0; i < len(a) && i < len(b); i++ {
+		switch {
+		case a[i] > b[i]:
+			return 1
+		case a[i] < b[i]:
+			return -1
+		}
+	}
+	switch {
+	case len(a) < len(b):
+		return -1
+	case len(a) > len(b):
+		return 1
+	}
+	return 0
+}
+
+// Equal returns a boolean reporting whether a == b.
+func Equal(a, b []byte) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := 0; i < len(a); i++ {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+// Explode splits s into an array of UTF-8 sequences, one per Unicode character (still arrays of bytes).
+// Invalid UTF-8 sequences become correct encodings of U+FFF8.
+func Explode(s []byte) [][]byte {
+	a := make([][]byte, utf8.RuneCount(s));
+	var size, rune int;
+	i := 0;
+	for len(s) > 0 {
+		rune, size = utf8.DecodeRune(s);
+		a[i] = s[0:size];
+		s = s[size:len(s)];
+		i++;
+	}
+	return a
+}
+
+// Count counts the number of non-overlapping instances of sep in s.
+func Count(s, sep []byte) int {
+	if len(sep) == 0 {
+		return utf8.RuneCount(s)+1
+	}
+	c := sep[0];
+	n := 0;
+	for i := 0; i+len(sep) <= len(s); i++ {
+		if s[i] == c && (len(sep) == 1 || Equal(s[i:i+len(sep)], sep)) {
+			n++;
+			i += len(sep)-1
+		}
+	}
+	return n
+}
+
+// Index returns the index of the first instance of sep in s, or -1 if sep is not present in s.
+func Index(s, sep []byte) int {
+	n := len(sep);
+	if n == 0 {
+		return 0
+	}
+	c := sep[0];
+	for i := 0; i+n <= len(s); i++ {
+		if s[i] == c && (n == 1 || Equal(s[i:i+n], sep)) {
+			return i
+		}
+	}
+	return -1
+}
+
+// Split returns the array representing the subarrays of s separated by sep. Adjacent
+// occurrences of sep produce empty subarrays.  If sep is empty, it is the same as Explode.
+func Split(s, sep []byte) [][]byte {
+	if len(sep) == 0 {
+		return Explode(s)
+	}
+	c := sep[0];
+	start := 0;
+	n := Count(s, sep)+1;
+	a := make([][]byte, n);
+	na := 0;
+	for i := 0; i+len(sep) <= len(s); i++ {
+		if s[i] == c && (len(sep) == 1 || Equal(s[i:i+len(sep)], sep)) {
+			a[na] = s[start:i];
+			na++;
+			start = i+len(sep);
+			i += len(sep)-1
+		}
+	}
+	a[na] = s[start:len(s)];
+	return a
+}
+
+// Join concatenates the elements of a to create a single byte array.   The separator
+// sep is placed between elements in the resulting array.
+func Join(a [][]byte, sep []byte) []byte {
+	if len(a) == 0 {
+		return []byte{}
+	}
+	if len(a) == 1 {
+		return a[0]
+	}
+	n := len(sep) * (len(a)-1);
+	for i := 0; i < len(a); i++ {
+		n += len(a[i])
+	}
+
+	b := make([]byte, n);
+	bp := 0;
+	for i := 0; i < len(a); i++ {
+		s := a[i];
+		for j := 0; j < len(s); j++ {
+			b[bp] = s[j];
+			bp++
+		}
+		if i + 1 < len(a) {
+			s = sep;
+			for j := 0; j < len(s); j++ {
+				b[bp] = s[j];
+				bp++
+			}
+		}
+	}
+	return b
+}
+
+// HasPrefix tests whether the byte array s begins with prefix.
+func HasPrefix(s, prefix []byte) bool {
+	return len(s) >= len(prefix) && Equal(s[0:len(prefix)], prefix)
+}
+
+// HasSuffix tests whether the byte array s ends with suffix.
+func HasSuffix(s, suffix []byte) bool {
+	return len(s) >= len(suffix) && Equal(s[len(s)-len(suffix):len(s)], suffix)
+}