From d3013d8aa1cbea6a74cbaaa8d4fe51d09db0386d Mon Sep 17 00:00:00 2001 From: Rob Pike Date: Sun, 13 Sep 2009 21:35:18 -0700 Subject: Add and AddByte R=rsc DELTA=83 (83 added, 0 deleted, 0 changed) OCL=34584 CL=34584 --- src/pkg/bytes/bytes.go | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) (limited to 'src/pkg/bytes/bytes.go') diff --git a/src/pkg/bytes/bytes.go b/src/pkg/bytes/bytes.go index 5375fecaa2..52aa8cdf40 100644 --- a/src/pkg/bytes/bytes.go +++ b/src/pkg/bytes/bytes.go @@ -260,3 +260,45 @@ func TrimSpace(s []byte) []byte { } return s[start:end]; } + +// How big to make a byte array when growing. +// Heuristic: Scale by 50% to give n log n time. +func resize(n int) int { + if n < 16 { + n = 16 + } + return n + n/2; +} + +// Add appends the contents of t to the end of s and returns the result. +// If s has enough capacity, it is extended in place; otherwise a +// new array is allocated and returned. +func Add(s, t []byte) []byte { + lens := len(s); + lent := len(t); + if lens + lent <= cap(s) { + s = s[0:lens+lent]; + } else { + news := make([]byte, lens+lent, resize(lens+lent)); + Copy(news, s); + s = news; + } + Copy(s[lens:lens+lent], t); + return s; +} + +// AddByte appends byte b to the end of s and returns the result. +// If s has enough capacity, it is extended in place; otherwise a +// new array is allocated and returned. +func AddByte(s []byte, t byte) []byte { + lens := len(s); + if lens + 1 <= cap(s) { + s = s[0:lens+1]; + } else { + news := make([]byte, lens+1, resize(lens+1)); + Copy(news, s); + s = news; + } + s[lens] = t; + return s; +} -- cgit v1.3-5-g9baa