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gitea-fork-majority-judgment/vendor/github.com/huandu/xstrings/format.go

171 lines
4.1 KiB

// Copyright 2015 Huan Du. All rights reserved.
// Licensed under the MIT license that can be found in the LICENSE file.
package xstrings
import (
"bytes"
"unicode/utf8"
)
// ExpandTabs can expand tabs ('\t') rune in str to one or more spaces dpending on
// current column and tabSize.
// The column number is reset to zero after each newline ('\n') occurring in the str.
//
// ExpandTabs uses RuneWidth to decide rune's width.
// For example, CJK characters will be treated as two characters.
//
// If tabSize <= 0, ExpandTabs panics with error.
//
// Samples:
// ExpandTabs("a\tbc\tdef\tghij\tk", 4) => "a bc def ghij k"
// ExpandTabs("abcdefg\thij\nk\tl", 4) => "abcdefg hij\nk l"
// ExpandTabs("z中\t文\tw", 4) => "z中 文 w"
func ExpandTabs(str string, tabSize int) string {
if tabSize <= 0 {
panic("tab size must be positive")
}
var r rune
var i, size, column, expand int
var output *bytes.Buffer
orig := str
for len(str) > 0 {
r, size = utf8.DecodeRuneInString(str)
if r == '\t' {
expand = tabSize - column%tabSize
if output == nil {
output = allocBuffer(orig, str)
}
for i = 0; i < expand; i++ {
output.WriteByte(byte(' '))
}
column += expand
} else {
if r == '\n' {
column = 0
} else {
column += RuneWidth(r)
}
if output != nil {
output.WriteRune(r)
}
}
str = str[size:]
}
if output == nil {
return orig
}
return output.String()
}
// LeftJustify returns a string with pad string at right side if str's rune length is smaller than length.
// If str's rune length is larger than length, str itself will be returned.
//
// If pad is an empty string, str will be returned.
//
// Samples:
// LeftJustify("hello", 4, " ") => "hello"
// LeftJustify("hello", 10, " ") => "hello "
// LeftJustify("hello", 10, "123") => "hello12312"
func LeftJustify(str string, length int, pad string) string {
l := Len(str)
if l >= length || pad == "" {
return str
}
remains := length - l
padLen := Len(pad)
output := &bytes.Buffer{}
output.Grow(len(str) + (remains/padLen+1)*len(pad))
output.WriteString(str)
writePadString(output, pad, padLen, remains)
return output.String()
}
// RightJustify returns a string with pad string at left side if str's rune length is smaller than length.
// If str's rune length is larger than length, str itself will be returned.
//
// If pad is an empty string, str will be returned.
//
// Samples:
// RightJustify("hello", 4, " ") => "hello"
// RightJustify("hello", 10, " ") => " hello"
// RightJustify("hello", 10, "123") => "12312hello"
func RightJustify(str string, length int, pad string) string {
l := Len(str)
if l >= length || pad == "" {
return str
}
remains := length - l
padLen := Len(pad)
output := &bytes.Buffer{}
output.Grow(len(str) + (remains/padLen+1)*len(pad))
writePadString(output, pad, padLen, remains)
output.WriteString(str)
return output.String()
}
// Center returns a string with pad string at both side if str's rune length is smaller than length.
// If str's rune length is larger than length, str itself will be returned.
//
// If pad is an empty string, str will be returned.
//
// Samples:
// Center("hello", 4, " ") => "hello"
// Center("hello", 10, " ") => " hello "
// Center("hello", 10, "123") => "12hello123"
func Center(str string, length int, pad string) string {
l := Len(str)
if l >= length || pad == "" {
return str
}
remains := length - l
padLen := Len(pad)
output := &bytes.Buffer{}
output.Grow(len(str) + (remains/padLen+1)*len(pad))
writePadString(output, pad, padLen, remains/2)
output.WriteString(str)
writePadString(output, pad, padLen, (remains+1)/2)
return output.String()
}
func writePadString(output *bytes.Buffer, pad string, padLen, remains int) {
var r rune
var size int
repeats := remains / padLen
for i := 0; i < repeats; i++ {
output.WriteString(pad)
}
remains = remains % padLen
if remains != 0 {
for i := 0; i < remains; i++ {
r, size = utf8.DecodeRuneInString(pad)
output.WriteRune(r)
pad = pad[size:]
}
}
}