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package test
import (
"fmt"
"strings"
"github.com/evanw/esbuild/internal/logger"
)
func diff(old string, new string, color bool) string {
return strings.Join(diffRec(nil, strings.Split(old, "\n"), strings.Split(new, "\n"), color), "\n")
}
// This is a simple recursive line-by-line diff implementation
func diffRec(result []string, old []string, new []string, color bool) []string {
o, n, common := lcSubstr(old, new)
if common == 0 {
// Everything changed
for _, line := range old {
if color {
result = append(result, fmt.Sprintf("%s-%s%s", logger.TerminalColors.Red, line, logger.TerminalColors.Reset))
} else {
result = append(result, "-"+line)
}
}
for _, line := range new {
if color {
result = append(result, fmt.Sprintf("%s+%s%s", logger.TerminalColors.Green, line, logger.TerminalColors.Reset))
} else {
result = append(result, "+"+line)
}
}
} else {
// Something in the middle stayed the same
result = diffRec(result, old[:o], new[:n], color)
for _, line := range old[o : o+common] {
if color {
result = append(result, fmt.Sprintf("%s %s%s", logger.TerminalColors.Dim, line, logger.TerminalColors.Reset))
} else {
result = append(result, " "+line)
}
}
result = diffRec(result, old[o+common:], new[n+common:], color)
}
return result
}
// From: https://en.wikipedia.org/wiki/Longest_common_substring_problem
func lcSubstr(S []string, T []string) (int, int, int) {
r := len(S)
n := len(T)
Lprev := make([]int, n)
Lnext := make([]int, n)
z := 0
retI := 0
retJ := 0
for i := 0; i < r; i++ {
for j := 0; j < n; j++ {
if S[i] == T[j] {
if j == 0 {
Lnext[j] = 1
} else {
Lnext[j] = Lprev[j-1] + 1
}
if Lnext[j] > z {
z = Lnext[j]
retI = i + 1
retJ = j + 1
}
} else {
Lnext[j] = 0
}
}
Lprev, Lnext = Lnext, Lprev
}
return retI - z, retJ - z, z
}
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