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Added template-expansion utility. (#10)
* Added template-expansion utility. * And test-cases. * Use our new template library for command-line expansion This closes #9
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,124 @@ | ||
| // Package templatedcmd allows expanding command-lines via a simple | ||
| // template-expansion process. | ||
| // | ||
| // For example the user might wish to run a command with an argument | ||
| // like so: | ||
| // | ||
| // command {} | ||
| // | ||
| // But we also support expanding the input into fields, and selecting | ||
| // only a single one, as per: | ||
| // | ||
| // $ echo "one two" | echo {1} | ||
| // # -> "one" | ||
| // | ||
| // All arguments are available via "{}" and "{N}" will refer to the | ||
| // Nth field of the given input. | ||
| // | ||
| package templatedcmd | ||
|
|
||
| import ( | ||
| "regexp" | ||
| "strconv" | ||
| "strings" | ||
| ) | ||
|
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| // Expand performs the expansion of the given input, via the supplied | ||
| // template. As we allow input to be referred to as an array of fields | ||
| // we also let the user specify a split-string here. | ||
| // | ||
| // By default the input is split on whitespace, but you may supply another | ||
| // string instead. | ||
| func Expand(template string, input string, split string) []string { | ||
|
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||
| // | ||
| // Regular expression for looking for ${1}, "${2}", "${3}", etc. | ||
| // | ||
| reg := regexp.MustCompile("({[0-9]+})") | ||
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||
| // | ||
| // Trim our input of leading/trailing spaces. | ||
| // | ||
| input = strings.TrimSpace(input) | ||
|
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||
| // | ||
| // Default to splitting the input on white-space. | ||
| // | ||
| fields := strings.Fields(input) | ||
| if split != "" { | ||
| fields = strings.Split(input, split) | ||
| } | ||
|
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||
| // | ||
| // The return-value is an array of strings | ||
| // | ||
| cmd := []string{} | ||
|
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| // | ||
| // We'll operate upon a temporary copy of our template, | ||
| // split into fields. | ||
| // | ||
| cmdTmp := strings.Fields(template) | ||
|
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||
| // | ||
| // For each piece of the template-string look for | ||
| // "{}", and "{N}", expand appropriately. | ||
| // | ||
| for _, piece := range cmdTmp { | ||
|
|
||
| // | ||
| // Do we have a "{N}" ? | ||
| // | ||
| matches := reg.FindAllStringSubmatch(piece, -1) | ||
|
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| // | ||
| // If so for each match, perform the expansion | ||
| // | ||
| for _, v := range matches { | ||
|
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| // | ||
| // Copy the match and remove the {} | ||
| // | ||
| // So we just have "1", "3", etc. | ||
| // | ||
| match := v[1] | ||
| match = strings.ReplaceAll(match, "{", "") | ||
| match = strings.ReplaceAll(match, "}", "") | ||
|
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| // | ||
| // Convert the string to a number, and if that | ||
| // worked we'll replace it with the appropriately | ||
| // numbered field. | ||
| // | ||
| num, err := strconv.Atoi(match) | ||
| if err == nil { | ||
|
|
||
| // | ||
| // If the field matches then we can replace it | ||
| // | ||
| if num >= 1 && num <= len(fields) { | ||
| piece = strings.ReplaceAll(piece, v[1], fields[num-1]) | ||
| } else { | ||
| // | ||
| // Otherwise it's a field that doesn't | ||
| // exist. So it's replaced with ''. | ||
| // | ||
| piece = strings.ReplaceAll(piece, v[1], "") | ||
| } | ||
| } | ||
| } | ||
|
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| // | ||
| // Now replace "{}" with the complete argument | ||
| // | ||
| piece = strings.ReplaceAll(piece, "{}", input) | ||
|
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| // And append | ||
| cmd = append(cmd, piece) | ||
| } | ||
|
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| // | ||
| // Now we should have an array of expanded strings. | ||
| // | ||
| return cmd | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,41 @@ | ||
| package templatedcmd | ||
|
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||
| import ( | ||
| "testing" | ||
| ) | ||
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| // Basic test | ||
| func TestBasic(t *testing.T) { | ||
|
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| type TestCase struct { | ||
| template string | ||
| input string | ||
| split string | ||
| expected []string | ||
| } | ||
|
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| tests := []TestCase{ | ||
| {"xine {}", "This is a file", "", []string{"xine", "This is a file"}}, | ||
| {"xine {1}", "This is a file", "", []string{"xine", "This"}}, | ||
| {"xine {3}", "This is a file", "", []string{"xine", "a"}}, | ||
| {"xine {10}", "This is a file", "", []string{"xine", ""}}, | ||
| {"foo bar", "", "", []string{"foo", "bar"}}, | ||
| {"id {1}", "root:0:0...", ":", []string{"id", "root"}}, | ||
| } | ||
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| for _, test := range tests { | ||
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| out := Expand(test.template, test.input, test.split) | ||
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| if len(out) != len(test.expected) { | ||
| t.Fatalf("Expected to have %d pieces, found %d", len(test.expected), len(out)) | ||
| } | ||
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| for i, x := range test.expected { | ||
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| if out[i] != x { | ||
| t.Errorf("expected '%s' for piece %d, got '%s'", x, i, out[i]) | ||
| } | ||
| } | ||
| } | ||
| } |