Port str capitalize (#317)

* Port str capitalize command

* Keep consistent naming for str commands

Co-authored-by: Stefan Stanciulescu <contact@stefanstanciulescu.com>

crates/nu-command/src/default_context.rs

@@ -95,6 +95,7 @@ pub fn create_default_context() -> EngineState {
             SplitRow,
             Str,
             StrCamelCase,
+            StrCapitalize,
             StrCollect,
             StrKebabCase,
             StrPascalCase,

crates/nu-command/src/strings/str_/capitalize.rs

@@ -0,0 +1,142 @@
+use nu_engine::CallExt;
+use nu_protocol::ast::Call;
+use nu_protocol::ast::CellPath;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{Example, PipelineData, ShellError, Signature, Span, SyntaxShape, Value};
+
+#[derive(Clone)]
+pub struct SubCommand;
+
+impl Command for SubCommand {
+    fn name(&self) -> &str {
+        "str capitalize"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("str capitalize").rest(
+            "rest",
+            SyntaxShape::CellPath,
+            "optionally capitalize text by column paths",
+        )
+    }
+
+    fn usage(&self) -> &str {
+        "capitalizes text"
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        operate(engine_state, stack, call, input)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Capitalize contents",
+                example: "'good day' | str capitalize",
+                result: Some(Value::String {
+                    val: "Good day".to_string(),
+                    span: Span::unknown(),
+                }),
+            },
+            Example {
+                description: "Capitalize contents",
+                example: "'anton' | str capitalize",
+                result: Some(Value::String {
+                    val: "Anton".to_string(),
+                    span: Span::unknown(),
+                }),
+            },
+            Example {
+                description: "Capitalize a column in a table",
+                example: "[[lang, gems]; [nu_test, 100]] | str capitalize lang",
+                result: Some(Value::List {
+                    vals: vec![Value::Record {
+                        span: Span::unknown(),
+                        cols: vec!["lang".to_string(), "gems".to_string()],
+                        vals: vec![
+                            Value::String {
+                                val: "Nu_test".to_string(),
+                                span: Span::unknown(),
+                            },
+                            Value::test_int(100),
+                        ],
+                    }],
+                    span: Span::unknown(),
+                }),
+            },
+        ]
+    }
+}
+
+fn operate(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    call: &Call,
+    input: PipelineData,
+) -> Result<PipelineData, ShellError> {
+    let head = call.head;
+    let column_paths: Vec<CellPath> = call.rest(engine_state, stack, 0)?;
+    input.map(
+        move |v| {
+            if column_paths.is_empty() {
+                action(&v, head)
+            } else {
+                let mut ret = v;
+                for path in &column_paths {
+                    let r =
+                        ret.update_cell_path(&path.members, Box::new(move |old| action(old, head)));
+                    if let Err(error) = r {
+                        return Value::Error { error };
+                    }
+                }
+                ret
+            }
+        },
+        engine_state.ctrlc.clone(),
+    )
+}
+
+fn action(input: &Value, head: Span) -> Value {
+    match input {
+        Value::String { val, .. } => Value::String {
+            val: uppercase_helper(val),
+            span: head,
+        },
+        other => Value::Error {
+            error: ShellError::UnsupportedInput(
+                format!(
+                    "Input's type is {}. This command only works with strings.",
+                    other.get_type()
+                ),
+                Span::unknown(),
+            ),
+        },
+    }
+}
+
+fn uppercase_helper(s: &str) -> String {
+    // apparently more performant https://stackoverflow.com/questions/38406793/why-is-capitalizing-the-first-letter-of-a-string-so-convoluted-in-rust
+    let mut chars = s.chars();
+    match chars.next() {
+        None => String::new(),
+        Some(f) => f.to_uppercase().collect::<String>() + chars.as_str(),
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        use crate::test_examples;
+
+        test_examples(SubCommand {})
+    }
+}

crates/nu-command/src/strings/str_/mod.rs

@@ -1,5 +1,7 @@
+mod capitalize;
 mod case;
 mod collect;
 
+pub use capitalize::SubCommand as StrCapitalize;
 pub use case::*;
 pub use collect::*;