Port parse command (#338)

crates/nu-command/src/default_context.rs

@@ -88,6 +88,7 @@ pub fn create_default_context() -> EngineState {
             Module,
             Mv,
             ParEach,
+            Parse,
             Ps,
             Range,
             Reverse,

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

@@ -1,11 +1,13 @@
 mod build_string;
 mod format;
+mod parse;
 mod size;
 mod split;
 mod str_;
 
 pub use build_string::BuildString;
 pub use format::*;
+pub use parse::*;
 pub use size::Size;
 pub use split::*;
 pub use str_::*;

crates/nu-command/src/strings/parse.rs

@@ -0,0 +1,236 @@
+use nu_engine::CallExt;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EngineState, Stack};
+use nu_protocol::{
+    Example, PipelineData, ShellError, Signature, Span, Spanned, SyntaxShape, Type, Value,
+    ValueStream,
+};
+use regex::Regex;
+
+#[derive(Clone)]
+pub struct Parse;
+
+impl Command for Parse {
+    fn name(&self) -> &str {
+        "parse"
+    }
+
+    fn usage(&self) -> &str {
+        "Parse columns from string data using a simple pattern."
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("parse")
+            .required(
+                "pattern",
+                SyntaxShape::String,
+                "the pattern to match. Eg) \"{foo}: {bar}\"",
+            )
+            .switch("regex", "use full regex syntax for patterns", Some('r'))
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        let result = Value::List {
+            vals: vec![Value::Record {
+                cols: vec!["foo".to_string(), "bar".to_string()],
+                vals: vec![Value::test_string("hi"), Value::test_string("there")],
+                span: Span::unknown(),
+            }],
+            span: Span::unknown(),
+        };
+
+        vec![
+            Example {
+                description: "Parse a string into two named columns",
+                example: "echo \"hi there\" | parse \"{foo} {bar}\"",
+                result: Some(result.clone()),
+            },
+            Example {
+                description: "Parse a string using regex pattern",
+                example: "echo \"hi there\" | parse -r \"(?P<foo>\\w+) (?P<bar>\\w+)\"",
+                result: Some(result),
+            },
+        ]
+    }
+
+    fn run(
+        &self,
+        engine_state: &EngineState,
+        stack: &mut Stack,
+        call: &Call,
+        input: PipelineData,
+    ) -> Result<PipelineData, ShellError> {
+        operate(engine_state, stack, call, input)
+    }
+}
+
+fn operate(
+    engine_state: &EngineState,
+    stack: &mut Stack,
+    call: &Call,
+    input: PipelineData,
+) -> Result<PipelineData, ShellError> {
+    let head = call.head;
+    let pattern: Spanned<String> = call.req(engine_state, stack, 0)?;
+    let regex: bool = call.has_flag("regex");
+
+    let pattern_item = pattern.item;
+    let pattern_span = pattern.span;
+
+    let item_to_parse = if regex {
+        pattern_item
+    } else {
+        build_regex(&pattern_item, pattern_span)?
+    };
+
+    let regex_pattern =
+        Regex::new(&item_to_parse).map_err(|e| parse_regex_error(e, pattern_span))?;
+
+    let columns = column_names(&regex_pattern);
+    let mut parsed: Vec<Value> = Vec::new();
+
+    for v in input {
+        match v.as_string() {
+            Ok(s) => {
+                let results = regex_pattern.captures_iter(&s);
+
+                for c in results {
+                    let mut cols = Vec::with_capacity(columns.len());
+                    let mut vals = Vec::with_capacity(c.len());
+
+                    for (column_name, cap) in columns.iter().zip(c.iter().skip(1)) {
+                        let cap_string = cap.map(|v| v.as_str()).unwrap_or("").to_string();
+                        cols.push(column_name.clone());
+                        vals.push(Value::String {
+                            val: cap_string,
+                            span: v.span()?,
+                        });
+                    }
+
+                    parsed.push(Value::Record {
+                        cols,
+                        vals,
+                        span: head,
+                    });
+                }
+            }
+            Err(_) => {
+                return Err(ShellError::PipelineMismatch {
+                    expected: Type::String,
+                    expected_span: head,
+                    origin: v.span()?,
+                })
+            }
+        }
+    }
+
+    Ok(PipelineData::Stream(ValueStream::from_stream(
+        parsed.into_iter(),
+        None,
+    )))
+}
+
+fn build_regex(input: &str, span: Span) -> Result<String, ShellError> {
+    let mut output = "(?s)\\A".to_string();
+
+    //let mut loop_input = input;
+    let mut loop_input = input.chars().peekable();
+    loop {
+        let mut before = String::new();
+        while let Some(c) = loop_input.next() {
+            if c == '{' {
+                // If '{{', still creating a plaintext parse command, but just for a single '{' char
+                if loop_input.peek() == Some(&'{') {
+                    let _ = loop_input.next();
+                } else {
+                    break;
+                }
+            }
+            before.push(c);
+        }
+
+        if !before.is_empty() {
+            output.push_str(&regex::escape(&before));
+        }
+
+        // Look for column as we're now at one
+        let mut column = String::new();
+        while let Some(c) = loop_input.next() {
+            if c == '}' {
+                break;
+            }
+            column.push(c);
+
+            if loop_input.peek().is_none() {
+                return Err(ShellError::DelimiterError(
+                    "Found opening `{` without an associated closing `}`".to_owned(),
+                    span,
+                ));
+            }
+        }
+
+        if !column.is_empty() {
+            output.push_str("(?P<");
+            output.push_str(&column);
+            output.push_str(">.*?)");
+        }
+
+        if before.is_empty() && column.is_empty() {
+            break;
+        }
+    }
+
+    output.push_str("\\z");
+    Ok(output)
+}
+
+fn column_names(regex: &Regex) -> Vec<String> {
+    regex
+        .capture_names()
+        .enumerate()
+        .skip(1)
+        .map(|(i, name)| {
+            name.map(String::from)
+                .unwrap_or_else(|| format!("Capture{}", i))
+        })
+        .collect()
+}
+
+fn parse_regex_error(e: regex::Error, base_span: Span) -> ShellError {
+    match e {
+        regex::Error::Syntax(msg) => {
+            let mut lines = msg.lines();
+
+            let main_msg = lines
+                .next()
+                .map(|l| l.replace(':', ""))
+                .expect("invalid regex pattern");
+
+            let span = lines.nth(1).and_then(|l| l.find('^')).map(|space| {
+                let start = base_span.start + space - 3;
+                Span::new(start, start + 1)
+            });
+
+            let msg = lines
+                .next()
+                .and_then(|l| l.split(':').nth(1))
+                .map(|s| format!("{}: {}", main_msg, s.trim()));
+
+            match (msg, span) {
+                (Some(msg), Some(span)) => ShellError::DelimiterError(msg, span),
+                _ => ShellError::DelimiterError("Invalid regex".to_owned(), base_span),
+            }
+        }
+        _ => ShellError::DelimiterError("Invalid regex".to_owned(), base_span),
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_examples() {
+        crate::test_examples(Parse)
+    }
+}