From 24b979c8219f45ede57f304c5e6029619829cf15 Mon Sep 17 00:00:00 2001
From: Daniel Hofstetter <daniel.hofstetter@42dh.com>
Date: Wed, 14 Jun 2023 10:35:13 +0200
Subject: [PATCH] uucore: introduce ShortcutValueParser

---
 src/uucore/src/lib/lib.rs                     |   1 +
 src/uucore/src/lib/parser.rs                  |   1 +
 .../src/lib/parser/shortcut_value_parser.rs   | 141 ++++++++++++++++++
 3 files changed, 143 insertions(+)
 create mode 100644 src/uucore/src/lib/parser/shortcut_value_parser.rs

diff --git a/src/uucore/src/lib/lib.rs b/src/uucore/src/lib/lib.rs
index e76e540c8..ca9a48d25 100644
--- a/src/uucore/src/lib/lib.rs
+++ b/src/uucore/src/lib/lib.rs
@@ -33,6 +33,7 @@ pub use crate::mods::version_cmp;
 pub use crate::parser::parse_glob;
 pub use crate::parser::parse_size;
 pub use crate::parser::parse_time;
+pub use crate::parser::shortcut_value_parser;
 
 // * feature-gated modules
 #[cfg(feature = "encoding")]
diff --git a/src/uucore/src/lib/parser.rs b/src/uucore/src/lib/parser.rs
index 8eae16bbf..fc3e46b5c 100644
--- a/src/uucore/src/lib/parser.rs
+++ b/src/uucore/src/lib/parser.rs
@@ -1,3 +1,4 @@
 pub mod parse_glob;
 pub mod parse_size;
 pub mod parse_time;
+pub mod shortcut_value_parser;
diff --git a/src/uucore/src/lib/parser/shortcut_value_parser.rs b/src/uucore/src/lib/parser/shortcut_value_parser.rs
new file mode 100644
index 000000000..0b0716158
--- /dev/null
+++ b/src/uucore/src/lib/parser/shortcut_value_parser.rs
@@ -0,0 +1,141 @@
+use clap::{
+    builder::{PossibleValue, TypedValueParser},
+    error::{ContextKind, ContextValue, ErrorKind},
+};
+
+#[derive(Clone)]
+pub struct ShortcutValueParser(Vec<PossibleValue>);
+
+/// `ShortcutValueParser` is similar to clap's `PossibleValuesParser`: it verifies that the value is
+/// from an enumerated set of `PossibleValue`.
+///
+/// Whereas `PossibleValuesParser` only accepts exact matches, `ShortcutValueParser` also accepts
+/// shortcuts as long as they are unambiguous.
+impl ShortcutValueParser {
+    pub fn new(values: impl Into<Self>) -> Self {
+        values.into()
+    }
+}
+
+impl TypedValueParser for ShortcutValueParser {
+    type Value = String;
+
+    fn parse_ref(
+        &self,
+        cmd: &clap::Command,
+        arg: Option<&clap::Arg>,
+        value: &std::ffi::OsStr,
+    ) -> Result<Self::Value, clap::Error> {
+        let value = value
+            .to_str()
+            .ok_or(clap::Error::new(ErrorKind::InvalidUtf8))?;
+
+        let matched_values: Vec<_> = self
+            .0
+            .iter()
+            .filter(|x| x.get_name().starts_with(value))
+            .collect();
+
+        if matched_values.len() == 1 {
+            Ok(matched_values[0].get_name().to_string())
+        } else {
+            let mut err = clap::Error::new(ErrorKind::InvalidValue).with_cmd(cmd);
+
+            if let Some(arg) = arg {
+                err.insert(
+                    ContextKind::InvalidArg,
+                    ContextValue::String(arg.to_string()),
+                );
+            }
+
+            err.insert(
+                ContextKind::InvalidValue,
+                ContextValue::String(value.to_string()),
+            );
+
+            err.insert(
+                ContextKind::ValidValue,
+                ContextValue::Strings(self.0.iter().map(|x| x.get_name().to_string()).collect()),
+            );
+
+            Err(err)
+        }
+    }
+
+    fn possible_values(&self) -> Option<Box<dyn Iterator<Item = PossibleValue> + '_>> {
+        Some(Box::new(self.0.iter().cloned()))
+    }
+}
+
+impl<I, T> From<I> for ShortcutValueParser
+where
+    I: IntoIterator<Item = T>,
+    T: Into<PossibleValue>,
+{
+    fn from(values: I) -> Self {
+        Self(values.into_iter().map(|t| t.into()).collect())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::ffi::OsStr;
+
+    use clap::{builder::TypedValueParser, error::ErrorKind, Command};
+
+    use super::ShortcutValueParser;
+
+    #[test]
+    fn test_parse_ref() {
+        let cmd = Command::new("cmd");
+        let parser = ShortcutValueParser::new(["abcd"]);
+        let values = ["a", "ab", "abc", "abcd"];
+
+        for value in values {
+            let result = parser.parse_ref(&cmd, None, OsStr::new(value));
+            assert_eq!("abcd", result.unwrap());
+        }
+    }
+
+    #[test]
+    fn test_parse_ref_with_invalid_value() {
+        let cmd = Command::new("cmd");
+        let parser = ShortcutValueParser::new(["abcd"]);
+        let invalid_values = ["e", "abe", "abcde"];
+
+        for invalid_value in invalid_values {
+            let result = parser.parse_ref(&cmd, None, OsStr::new(invalid_value));
+            assert_eq!(ErrorKind::InvalidValue, result.unwrap_err().kind());
+        }
+    }
+
+    #[test]
+    fn test_parse_ref_with_ambiguous_value() {
+        let cmd = Command::new("cmd");
+        let parser = ShortcutValueParser::new(["abcd", "abef"]);
+        let ambiguous_values = ["a", "ab"];
+
+        for ambiguous_value in ambiguous_values {
+            let result = parser.parse_ref(&cmd, None, OsStr::new(ambiguous_value));
+            assert_eq!(ErrorKind::InvalidValue, result.unwrap_err().kind());
+        }
+
+        let result = parser.parse_ref(&cmd, None, OsStr::new("abc"));
+        assert_eq!("abcd", result.unwrap());
+
+        let result = parser.parse_ref(&cmd, None, OsStr::new("abe"));
+        assert_eq!("abef", result.unwrap());
+    }
+
+    #[test]
+    #[cfg(unix)]
+    fn test_parse_ref_with_invalid_utf8() {
+        use std::os::unix::prelude::OsStrExt;
+
+        let parser = ShortcutValueParser::new(["abcd"]);
+        let cmd = Command::new("cmd");
+
+        let result = parser.parse_ref(&cmd, None, OsStr::from_bytes(&[0xc3 as u8, 0x28 as u8]));
+        assert_eq!(ErrorKind::InvalidUtf8, result.unwrap_err().kind());
+    }
+}