1 files changed, 126 insertions, 0 deletions
diff --git a/clap/src/completions/elvish.rs b/clap/src/completions/elvish.rs
new file mode 100644
index 0000000..9a5f21a
--- /dev/null
+++ b/clap/src/completions/elvish.rs
@@ -0,0 +1,126 @@
+// Std
+use std::io::Write;
+
+// Internal
+use app::parser::Parser;
+use INTERNAL_ERROR_MSG;
+
+pub struct ElvishGen<'a, 'b>
+where
+    'a: 'b,
+{
+    p: &'b Parser<'a, 'b>,
+}
+
+impl<'a, 'b> ElvishGen<'a, 'b> {
+    pub fn new(p: &'b Parser<'a, 'b>) -> Self { ElvishGen { p: p } }
+
+    pub fn generate_to<W: Write>(&self, buf: &mut W) {
+        let bin_name = self.p.meta.bin_name.as_ref().unwrap();
+
+        let mut names = vec![];
+        let subcommands_cases =
+            generate_inner(self.p, "", &mut names);
+
+        let result = format!(r#"
+edit:completion:arg-completer[{bin_name}] = [@words]{{
+    fn spaces [n]{{
+        repeat $n ' ' | joins ''
+    }}
+    fn cand [text desc]{{
+        edit:complex-candidate $text &display-suffix=' '(spaces (- 14 (wcswidth $text)))$desc
+    }}
+    command = '{bin_name}'
+    for word $words[1:-1] {{
+        if (has-prefix $word '-') {{
+            break
+        }}
+        command = $command';'$word
+    }}
+    completions = [{subcommands_cases}
+    ]
+    $completions[$command]
+}}
+"#,
+            bin_name = bin_name,
+            subcommands_cases = subcommands_cases
+        );
+
+        w!(buf, result.as_bytes());
+    }
+}
+
+// Escape string inside single quotes
+fn escape_string(string: &str) -> String { string.replace("'", "''") }
+
+fn get_tooltip<T : ToString>(help: Option<&str>, data: T) -> String {
+    match help {
+        Some(help) => escape_string(help),
+        _ => data.to_string()
+    }
+}
+
+fn generate_inner<'a, 'b, 'p>(
+    p: &'p Parser<'a, 'b>,
+    previous_command_name: &str,
+    names: &mut Vec<&'p str>,
+) -> String {
+    debugln!("ElvishGen::generate_inner;");
+    let command_name = if previous_command_name.is_empty() {
+        p.meta.bin_name.as_ref().expect(INTERNAL_ERROR_MSG).clone()
+    } else {
+        format!("{};{}", previous_command_name, &p.meta.name)
+    };
+
+    let mut completions = String::new();
+    let preamble = String::from("\n            cand ");
+
+    for option in p.opts() {
+        if let Some(data) = option.s.short {
+            let tooltip = get_tooltip(option.b.help, data);
+            completions.push_str(&preamble);
+            completions.push_str(format!("-{} '{}'", data, tooltip).as_str());
+        }
+        if let Some(data) = option.s.long {
+            let tooltip = get_tooltip(option.b.help, data);
+            completions.push_str(&preamble);
+            completions.push_str(format!("--{} '{}'", data, tooltip).as_str());
+        }
+    }
+
+    for flag in p.flags() {
+        if let Some(data) = flag.s.short {
+            let tooltip = get_tooltip(flag.b.help, data);
+            completions.push_str(&preamble);
+            completions.push_str(format!("-{} '{}'", data, tooltip).as_str());
+        }
+        if let Some(data) = flag.s.long {
+            let tooltip = get_tooltip(flag.b.help, data);
+            completions.push_str(&preamble);
+            completions.push_str(format!("--{} '{}'", data, tooltip).as_str());
+        }
+    }
+
+    for subcommand in &p.subcommands {
+        let data = &subcommand.p.meta.name;
+        let tooltip = get_tooltip(subcommand.p.meta.about, data);
+        completions.push_str(&preamble);
+        completions.push_str(format!("{} '{}'", data, tooltip).as_str());
+    }
+
+    let mut subcommands_cases = format!(
+        r"
+        &'{}'= {{{}
+        }}",
+        &command_name,
+        completions
+    );
+
+    for subcommand in &p.subcommands {
+        let subcommand_subcommands_cases =
+            generate_inner(&subcommand.p, &command_name, names);
+        subcommands_cases.push_str(&subcommand_subcommands_cases);
+    }
+
+    subcommands_cases
+}