1 files changed, 178 insertions, 0 deletions
diff --git a/src/pkg/strings/strings.go b/src/pkg/strings/strings.go
new file mode 100644
index 000000000..2e3dc0215
--- /dev/null
+++ b/src/pkg/strings/strings.go
@@ -0,0 +1,178 @@
+// 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 strings.
+package strings
+
+import "utf8"
+
+// Explode splits s into an array of UTF-8 sequences, one per Unicode character (still strings).
+// Invalid UTF-8 sequences become correct encodings of U+FFF8.
+func Explode(s string) []string {
+	a := make([]string, utf8.RuneCountInString(s));
+	var size, rune int;
+	i := 0;
+	for len(s) > 0 {
+		rune, size = utf8.DecodeRuneInString(s);
+		s = s[size:len(s)];
+		a[i] = string(rune);
+		i++;
+	}
+	return a
+}
+
+// Count counts the number of non-overlapping instances of sep in s.
+func Count(s, sep string) int {
+	if sep == "" {
+		return utf8.RuneCountInString(s)+1
+	}
+	c := sep[0];
+	n := 0;
+	for i := 0; i+len(sep) <= len(s); i++ {
+		if s[i] == c && (len(sep) == 1 || 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 string) 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 || s[i:i+n] == sep) {
+			return i
+		}
+	}
+	return -1
+}
+
+// Split returns the array representing the substrings of s separated by string sep. Adjacent
+// occurrences of sep produce empty substrings.  If sep is empty, it is the same as Explode.
+func Split(s, sep string) []string {
+	if sep == "" {
+		return Explode(s)
+	}
+	c := sep[0];
+	start := 0;
+	n := Count(s, sep)+1;
+	a := make([]string, n);
+	na := 0;
+	for i := 0; i+len(sep) <= len(s); i++ {
+		if s[i] == c && (len(sep) == 1 || 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 string.   The separator string
+// sep is placed between elements in the resulting string.
+func Join(a []string, sep string) string {
+	if len(a) == 0 {
+		return ""
+	}
+	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 string(b)
+}
+
+// HasPrefix tests whether the string s begins with prefix.
+func HasPrefix(s, prefix string) bool {
+	return len(s) >= len(prefix) && s[0:len(prefix)] == prefix
+}
+
+// HasSuffix tests whether the string s ends with suffix.
+func HasSuffix(s, suffix string) bool {
+	return len(s) >= len(suffix) && s[len(s)-len(suffix):len(s)] == suffix
+}
+
+// Upper returns a copy of the string s, with all low ASCII lowercase letters
+// converted to uppercase.
+// TODO: full Unicode support
+func UpperASCII(s string) string {
+	// Note, we can work byte-by-byte because UTF-8 multibyte characters
+	// don't use any low ASCII byte values.
+	b := make([]byte, len(s));
+	for i := 0; i < len(s); i++ {
+		c := s[i];
+		if 'a' <= c && c <= 'z' {
+			c -= 'a' - 'A';
+		}
+		b[i] = c;
+	}
+	return string(b);
+}
+
+// Upper returns a copy of the string s, with all low ASCII lowercase letters
+// converted to lowercase.
+// TODO: full Unicode support
+func LowerASCII(s string) string {
+	// Note, we can work byte-by-byte because UTF-8 multibyte characters
+	// don't use any low ASCII byte values.
+	b := make([]byte, len(s));
+	for i := 0; i < len(s); i++ {
+		c := s[i];
+		if 'A' <= c && c <= 'Z' {
+			c += 'a' - 'A';
+		}
+		b[i] = c;
+	}
+	return string(b);
+}
+
+func isWhitespaceASCII(c byte) bool {
+	switch int(c) {
+	case ' ', '\t', '\r', '\n':
+		return true;
+	}
+ 	return false;
+}
+
+// Trim returns a slice of the string s, with all leading and trailing whitespace
+// removed.  "Whitespace" for now defined as space, tab, CR, or LF.
+// TODO: full Unicode whitespace support (need a unicode.IsWhitespace method)
+func TrimSpaceASCII(s string) string {
+	// Note, we can work byte-by-byte because UTF-8 multibyte characters
+	// don't use any low ASCII byte values.
+	start, end := 0, len(s);
+	for start < end && isWhitespaceASCII(s[start]) {
+		start++;
+	}
+	for start < end && isWhitespaceASCII(s[end-1]) {
+		end--;
+	}
+	return s[start:end];
+}