| 🛟 Updated. 28d5985 k33g 14h ago | 1 | package tools |
| 2 | |
| 3 | import ( |
| 4 | "fmt" |
| 5 | "strings" |
| 6 | ) |
| 7 | |
| 8 | // A tool asks for a value by writing a placeholder into its command: |
| 9 | // |
| 10 | // command = "go mod init {{module path}}" |
| 11 | // |
| 12 | // The text between the braces is what the editor asks for. A trailing "..." |
| 13 | // means the value is substituted verbatim rather than shell-quoted, which is |
| 14 | // how one placeholder can stand for several arguments: |
| 15 | // |
| 16 | // command = "go test {{extra flags...}} ./..." |
| 17 | // |
| 18 | // **Double braces, not single.** Single ones appear in real commands — `awk |
| 19 | // '{print $1}'` and `find . -exec rm {} +` are both ordinary things to put in a |
| 20 | // tools file — and treating those as placeholders would turn a working command |
| 21 | // into a dialog asking for "print $1". |
| 22 | const ( |
| 23 | placeholderOpen = "{{" |
| 24 | placeholderClose = "}}" |
| 25 | // rawSuffix inside a placeholder asks for the value verbatim. |
| 26 | rawSuffix = "..." |
| 27 | ) |
| 28 | |
| 29 | // Placeholder is a value a tool asks for before it runs. |
| 30 | type Placeholder struct { |
| 31 | // Label is what the editor asks for: the text between the braces, trimmed, |
| 32 | // with any trailing "..." removed. |
| 33 | Label string |
| 34 | // Raw says the value is substituted verbatim rather than shell-quoted. |
| 35 | // |
| 36 | // A label written both ways in one command — `{{x}}` here and `{{x...}}` |
| 37 | // there — is asked for once and substituted according to *each* occurrence, |
| 38 | // so this reports what the first occurrence asked for. |
| 39 | Raw bool |
| 40 | } |
| 41 | |
| 42 | // Placeholders returns the values a tool's command asks for, in the order they |
| 43 | // first appear, with a label used twice reported once. |
| 44 | // |
| 45 | // A command with none gives nothing, which is what makes an ordinary tool run |
| 46 | // straight away rather than opening an empty box. |
| 47 | // |
| 48 | // tools.Tool{Command: "go mod init {{module path}}"}.Placeholders() |
| 49 | // // [{Label: "module path"}] |
| 50 | func (t Tool) Placeholders() []Placeholder { |
| 51 | found, err := parsePlaceholders(t.Command) |
| 52 | if err != nil { |
| 53 | // Load refuses a command this cannot parse, so a Tool that came from a |
| 54 | // file never reaches here with a broken one. A Tool built in code might; |
| 55 | // asking for nothing is the safe answer, and running it unchanged shows |
| 56 | // the braces rather than silently dropping them. |
| 57 | return nil |
| 58 | } |
| 59 | |
| 60 | var out []Placeholder |
| 61 | seen := map[string]bool{} |
| 62 | for _, p := range found { |
| 63 | if seen[p.Label] { |
| 64 | continue |
| 65 | } |
| 66 | seen[p.Label] = true |
| 67 | out = append(out, Placeholder{Label: p.Label, Raw: p.Raw}) |
| 68 | } |
| 69 | return out |
| 70 | } |
| 71 | |
| 72 | // Fill returns the command with every placeholder replaced by the value given |
| 73 | // for its label. |
| 74 | // |
| 75 | // A value is **shell-quoted** unless its placeholder asked to be raw, because |
| 76 | // the result is handed to `sh -c` and a value with a space in it silently |
| 77 | // becoming two arguments is a bug nobody can see. A label with no value in the |
| 78 | // map is replaced by nothing, which lets a command report its own complaint |
| 79 | // rather than the editor guessing what an empty field meant. |
| 80 | // |
| 81 | // tool := tools.Tool{Command: "go build -o {{output}}"} |
| 82 | // tool.Fill(map[string]string{"output": "my binary"}) |
| 83 | // // go build -o 'my binary' |
| 84 | func (t Tool) Fill(values map[string]string) string { |
| 85 | found, err := parsePlaceholders(t.Command) |
| 86 | if err != nil { |
| 87 | return t.Command |
| 88 | } |
| 89 | |
| 90 | var b strings.Builder |
| 91 | at := 0 |
| 92 | for _, p := range found { |
| 93 | b.WriteString(t.Command[at:p.start]) |
| 94 | b.WriteString(substitute(values[p.Label], p.Raw)) |
| 95 | at = p.end |
| 96 | } |
| 97 | b.WriteString(t.Command[at:]) |
| 98 | return b.String() |
| 99 | } |
| 100 | |
| 101 | // substitute renders one value into a command line. |
| 102 | func substitute(value string, raw bool) string { |
| 103 | if raw { |
| 104 | return value |
| 105 | } |
| 106 | return ShellQuote(value) |
| 107 | } |
| 108 | |
| 109 | // ShellQuote wraps a string so that `sh -c` sees it as exactly one argument, |
| 110 | // whatever is in it. |
| 111 | // |
| 112 | // Single quotes are used because nothing inside them is special to the shell — |
| 113 | // no expansion, no escapes — so the only case to handle is a single quote in |
| 114 | // the value itself, which ends the quoting, adds an escaped quote, and starts |
| 115 | // it again. |
| 116 | // |
| 117 | // tools.ShellQuote("it's here") // 'it'\''s here' |
| 118 | func ShellQuote(value string) string { |
| 119 | return "'" + strings.ReplaceAll(value, "'", `'\''`) + "'" |
| 120 | } |
| 121 | |
| 122 | // placeholderAt is one occurrence in a command, and where it sits. |
| 123 | type placeholderAt struct { |
| 124 | Label string |
| 125 | Raw bool |
| 126 | start int // byte offset of the opening brace |
| 127 | end int // byte offset just past the closing brace |
| 128 | } |
| 129 | |
| 130 | // parsePlaceholders finds every placeholder in a command, in order. |
| 131 | // |
| 132 | // It refuses a command it cannot make sense of rather than guessing: an opener |
| 133 | // with no closer is a half-typed placeholder, and a placeholder with no label |
| 134 | // is a box asking for nothing under a blank heading. Both are reported so the |
| 135 | // person who wrote the file finds out from the editor rather than from a |
| 136 | // command that ran with braces in it. |
| 137 | func parsePlaceholders(command string) ([]placeholderAt, error) { |
| 138 | var out []placeholderAt |
| 139 | at := 0 |
| 140 | |
| 141 | for { |
| 142 | open := strings.Index(command[at:], placeholderOpen) |
| 143 | if open < 0 { |
| 144 | return out, nil |
| 145 | } |
| 146 | open += at |
| 147 | |
| 148 | close := strings.Index(command[open:], placeholderClose) |
| 149 | if close < 0 { |
| 150 | return nil, fmt.Errorf("%q is never closed", command[open:]) |
| 151 | } |
| 152 | close += open |
| 153 | |
| 154 | inside := command[open+len(placeholderOpen) : close] |
| 155 | label, raw := splitRaw(inside) |
| 156 | if label == "" { |
| 157 | return nil, fmt.Errorf("%s%s%s asks for a value but does not say what it is", |
| 158 | placeholderOpen, inside, placeholderClose) |
| 159 | } |
| 160 | |
| 161 | out = append(out, placeholderAt{Label: label, Raw: raw, start: open, end: close + len(placeholderClose)}) |
| 162 | at = close + len(placeholderClose) |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | // splitRaw separates a placeholder's label from the "..." that asks for it |
| 167 | // verbatim. |
| 168 | func splitRaw(inside string) (label string, raw bool) { |
| 169 | trimmed := strings.TrimSpace(inside) |
| 170 | if after, found := strings.CutSuffix(trimmed, rawSuffix); found { |
| 171 | return strings.TrimSpace(after), true |
| 172 | } |
| 173 | return trimmed, false |
| 174 | } |
| 175 | |
| 176 | // checkPlaceholders reports what is wrong with a tool's placeholders, naming |
| 177 | // the tool and the file so the message says where to go. |
| 178 | func checkPlaceholders(tool Tool, path string) error { |
| 179 | if _, err := parsePlaceholders(tool.Command); err != nil { |
| 180 | return fmt.Errorf("reading %s: tool %q: %w", path, tool.Name, err) |
| 181 | } |
| 182 | return nil |
| 183 | } |