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Diffstat (limited to 'vendor/github.com/kr/text/wrap.go')
-rw-r--r-- | vendor/github.com/kr/text/wrap.go | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/vendor/github.com/kr/text/wrap.go b/vendor/github.com/kr/text/wrap.go new file mode 100644 index 000000000..b09bb0373 --- /dev/null +++ b/vendor/github.com/kr/text/wrap.go @@ -0,0 +1,86 @@ +package text + +import ( + "bytes" + "math" +) + +var ( + nl = []byte{'\n'} + sp = []byte{' '} +) + +const defaultPenalty = 1e5 + +// Wrap wraps s into a paragraph of lines of length lim, with minimal +// raggedness. +func Wrap(s string, lim int) string { + return string(WrapBytes([]byte(s), lim)) +} + +// WrapBytes wraps b into a paragraph of lines of length lim, with minimal +// raggedness. +func WrapBytes(b []byte, lim int) []byte { + words := bytes.Split(bytes.Replace(bytes.TrimSpace(b), nl, sp, -1), sp) + var lines [][]byte + for _, line := range WrapWords(words, 1, lim, defaultPenalty) { + lines = append(lines, bytes.Join(line, sp)) + } + return bytes.Join(lines, nl) +} + +// WrapWords is the low-level line-breaking algorithm, useful if you need more +// control over the details of the text wrapping process. For most uses, either +// Wrap or WrapBytes will be sufficient and more convenient. +// +// WrapWords splits a list of words into lines with minimal "raggedness", +// treating each byte as one unit, accounting for spc units between adjacent +// words on each line, and attempting to limit lines to lim units. Raggedness +// is the total error over all lines, where error is the square of the +// difference of the length of the line and lim. Too-long lines (which only +// happen when a single word is longer than lim units) have pen penalty units +// added to the error. +func WrapWords(words [][]byte, spc, lim, pen int) [][][]byte { + n := len(words) + + length := make([][]int, n) + for i := 0; i < n; i++ { + length[i] = make([]int, n) + length[i][i] = len(words[i]) + for j := i + 1; j < n; j++ { + length[i][j] = length[i][j-1] + spc + len(words[j]) + } + } + + nbrk := make([]int, n) + cost := make([]int, n) + for i := range cost { + cost[i] = math.MaxInt32 + } + for i := n - 1; i >= 0; i-- { + if length[i][n-1] <= lim || i == n-1 { + cost[i] = 0 + nbrk[i] = n + } else { + for j := i + 1; j < n; j++ { + d := lim - length[i][j-1] + c := d*d + cost[j] + if length[i][j-1] > lim { + c += pen // too-long lines get a worse penalty + } + if c < cost[i] { + cost[i] = c + nbrk[i] = j + } + } + } + } + + var lines [][][]byte + i := 0 + for i < n { + lines = append(lines, words[i:nbrk[i]]) + i = nbrk[i] + } + return lines +} |