Brace expansion using ranges: Difference between revisions

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 :* &nbsp; [[Range_expansion]]
 <br><br>
+=={{header|Go}}==
+{{trans|Wren}}
+<lang go>package main
+import (
+    "fmt"
+    "strconv"
+    "strings"
+    "unicode/utf8"
+)
+func parseRange(r string) []string {
+    if r == "" {
+        return []string{"{}"} // rangeless, empty
+    }
+    sp := strings.Split(r, "..")
+    if len(sp) == 1 {
+        return []string{"{" + r + "}"} // rangeless, random value
+    }
+    sta := sp[0]
+    end := sp[1]
+    inc := "1"
+    if len(sp) > 2 {
+        inc = sp[2]
+    }
+    n1, ok1 := strconv.Atoi(sta)
+    n2, ok2 := strconv.Atoi(end)
+    n3, ok3 := strconv.Atoi(inc)
+    if ok3 != nil {
+        return []string{"{" + r + "}"} // increment isn't a number
+    }
+    numeric := (ok1 == nil) && (ok2 == nil)
+    if !numeric {
+        if (ok1 == nil && ok2 != nil) || (ok1 != nil && ok2 == nil) {
+            return []string{"{" + r + "}"} // mixed numeric/alpha not expanded
+        }
+        if utf8.RuneCountInString(sta) != 1 || utf8.RuneCountInString(end) != 1 {
+            return []string{"{" + r + "}"} // start/end are not both single alpha
+        }
+        n1 = int(([]rune(sta))[0])
+        n2 = int(([]rune(end))[0])
+    }
+    width := 1
+    if numeric {
+        if len(sta) < len(end) {
+            width = len(end)
+        } else {
+            width = len(sta)
+        }
+    }
+    if n3 == 0 { // zero increment
+        if numeric {
+            return []string{fmt.Sprintf("%0*d", width, n1)}
+        } else {
+            return []string{sta}
+        }
+    }
+    var res []string
+    asc := n1 < n2
+    if n3 < 0 {
+        asc = !asc
+        n1, n2 = n2, n1
+        n3 = -n3
+    }
+    i := n1
+    if asc {
+        for ; i <= n2; i += n3 {
+            if numeric {
+                res = append(res, fmt.Sprintf("%0*d", width, i))
+            } else {
+                res = append(res, string(rune(i)))
+            }
+        }
+    } else {
+        for ; i >= n2; i -= n3 {
+            if numeric {
+                res = append(res, fmt.Sprintf("%0*d", width, i))
+            } else {
+                res = append(res, string(rune(i)))
+            }
+        }
+    }
+    return res
+}
+func rangeExpand(s string) []string {
+    res := []string{""}
+    rng := ""
+    inRng := false
+    for _, c := range s {
+        if c == '{' && !inRng {
+            inRng = true
+            rng = ""
+        } else if c == '}' && inRng {
+            rngRes := parseRange(rng)
+            rngLen := len(rngRes)
+            var res2 []string
+            for i := 0; i < len(res); i++ {
+                for j := 0; j < rngLen; j++ {
+                    res2 = append(res2, res[i]+rngRes[j])
+                }
+            }
+            res = res2
+            inRng = false
+        } else if inRng {
+            rng += string(c)
+        } else {
+            for i := 0; i < len(res); i++ {
+                res[i] += string(c)
+            }
+        }
+    }
+    if inRng {
+        for i := 0; i < len(res); i++ {
+            res[i] += "{" + rng // unmatched braces
+        }
+    }
+    return res
+}
+func main() {
+    examples := []string{
+        "simpleNumberRising{1..3}.txt",
+        "simpleAlphaDescending-{Z..X}.txt",
+        "steppedDownAndPadded-{10..00..5}.txt",
+        "minusSignFlipsSequence {030..20..-5}.txt",
+        "combined-{Q..P}{2..1}.txt",
+        "emoji{🌵..🌶}{🌽..🌾}etc",
+        "li{teral",
+        "rangeless{}empty",
+        "rangeless{random}string",
+        "mixedNumberAlpha{5..k}",
+        "steppedAlphaRising{P..Z..2}.txt",
+        "stops after endpoint-{02..10..3}.txt",
+    }
+    for _, s := range examples {
+        fmt.Print(s, "->\n    ")
+        res := rangeExpand(s)
+        fmt.Println(strings.Join(res, "\n    "))
+        fmt.Println()
+    }
+}</lang>
+{{out}}
+<pre>
+Same as Wren entry.
+</pre>
 =={{header|JavaScript}}==