Merge branch 'main' of https://github.com/nushell/engine-q into parse-error

Cargo.lock

@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "aho-corasick"
+version = "0.7.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e37cfd5e7657ada45f742d6e99ca5788580b5c529dc78faf11ece6dc702656f"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "ansi_term"
 version = "0.12.1"
@@ -148,6 +157,7 @@ dependencies = [
  "nu-engine",
  "nu-parser",
  "nu-protocol",
+ "nu-table",
  "pretty_assertions",
  "reedline",
  "tempfile",
@@ -164,6 +174,12 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "glob"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
+
 [[package]]
 name = "instant"
 version = "0.1.10"
@@ -276,8 +292,10 @@ dependencies = [
 name = "nu-command"
 version = "0.1.0"
 dependencies = [
+ "glob",
  "nu-engine",
  "nu-protocol",
+ "nu-table",
 ]
 
 [[package]]
@@ -303,6 +321,15 @@ dependencies = [
  "codespan-reporting",
 ]
 
+[[package]]
+name = "nu-table"
+version = "0.36.0"
+dependencies = [
+ "nu-ansi-term",
+ "regex",
+ "unicode-width",
+]
+
 [[package]]
 name = "num-integer"
 version = "0.1.44"
@@ -487,12 +514,29 @@ dependencies = [
  "unicode-width",
 ]
 
+[[package]]
+name = "regex"
+version = "1.5.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d07a8629359eb56f1e2fb1652bb04212c072a87ba68546a04065d525673ac461"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
 [[package]]
 name = "regex-automata"
 version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6c230d73fb8d8c1b9c0b3135c5142a8acee3a0558fb8db5cf1cb65f8d7862132"
 
+[[package]]
+name = "regex-syntax"
+version = "0.6.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f497285884f3fcff424ffc933e56d7cbca511def0c9831a7f9b5f6153e3cc89b"
+
 [[package]]
 name = "remove_dir_all"
 version = "0.5.3"

Cargo.toml

@@ -16,6 +16,7 @@ nu-command = { path="./crates/nu-command" }
 nu-engine = { path="./crates/nu-engine" }
 nu-parser = { path="./crates/nu-parser" }
 nu-protocol = { path = "./crates/nu-protocol" }
+nu-table = { path = "./crates/nu-table" }
 
 # mimalloc = { version = "*", default-features = false }
 

TODO.md

@@ -17,7 +17,8 @@
 - [x] Column path
 - [x] ...rest without calling it rest
 - [x] Iteration (`each`) over tables
-- [ ] Row conditions
+- [x] Row conditions
+- [x] Simple completions
 - [ ] Value serialization
 - [ ] Handling rows with missing columns during a cell path
 - [ ] Error shortcircuit (stopping on first error)

crates/nu-cli/src/completions.rs

@@ -0,0 +1,54 @@
+use std::{cell::RefCell, rc::Rc};
+
+use nu_parser::{flatten_block, parse};
+use nu_protocol::engine::{EngineState, StateWorkingSet};
+use reedline::Completer;
+
+pub struct NuCompleter {
+    engine_state: Rc<RefCell<EngineState>>,
+}
+
+impl NuCompleter {
+    pub fn new(engine_state: Rc<RefCell<EngineState>>) -> Self {
+        Self { engine_state }
+    }
+}
+
+impl Completer for NuCompleter {
+    fn complete(&self, line: &str, pos: usize) -> Vec<(reedline::Span, String)> {
+        let engine_state = self.engine_state.borrow();
+        let mut working_set = StateWorkingSet::new(&*engine_state);
+        let offset = working_set.next_span_start();
+        let pos = offset + pos;
+        let (output, _err) = parse(&mut working_set, Some("completer"), line.as_bytes(), false);
+
+        let flattened = flatten_block(&working_set, &output);
+
+        for flat in flattened {
+            if pos >= flat.0.start && pos <= flat.0.end {
+                match flat.1 {
+                    nu_parser::FlatShape::External | nu_parser::FlatShape::InternalCall => {
+                        let prefix = working_set.get_span_contents(flat.0);
+                        let results = working_set.find_commands_by_prefix(prefix);
+
+                        return results
+                            .into_iter()
+                            .map(move |x| {
+                                (
+                                    reedline::Span {
+                                        start: flat.0.start - offset,
+                                        end: flat.0.end - offset,
+                                    },
+                                    String::from_utf8_lossy(&x).to_string(),
+                                )
+                            })
+                            .collect();
+                    }
+                    _ => {}
+                }
+            }
+        }
+
+        vec![]
+    }
+}

crates/nu-cli/src/lib.rs

@@ -1,5 +1,7 @@
+mod completions;
 mod errors;
 mod syntax_highlight;
 
+pub use completions::NuCompleter;
 pub use errors::{report_parsing_error, report_shell_error};
 pub use syntax_highlight::NuHighlighter;

crates/nu-command/Cargo.toml

@@ -7,4 +7,8 @@ edition = "2018"
 
 [dependencies]
 nu-protocol = { path = "../nu-protocol" }
-nu-engine = { path = "../nu-engine" }
+nu-engine = { path = "../nu-engine" }
+nu-table = { path = "../nu-table" }
+
+# Potential dependencies for extras
+glob = "0.3.0"

crates/nu-command/src/default_context.rs

@@ -5,7 +5,10 @@ use nu_protocol::{
     Signature, SyntaxShape,
 };
 
-use crate::{Alias, Benchmark, BuildString, Def, Do, Each, For, If, Length, Let, LetEnv};
+use crate::{
+    where_::Where, Alias, Benchmark, BuildString, Def, Do, Each, For, If, Length, Let, LetEnv, Ls,
+    Table,
+};
 
 pub fn create_default_context() -> Rc<RefCell<EngineState>> {
     let engine_state = Rc::new(RefCell::new(EngineState::new()));
@@ -33,12 +36,18 @@ pub fn create_default_context() -> Rc<RefCell<EngineState>> {
 
         working_set.add_decl(Box::new(Each));
 
+        working_set.add_decl(Box::new(Where));
+
         working_set.add_decl(Box::new(Do));
 
         working_set.add_decl(Box::new(Benchmark));
 
         working_set.add_decl(Box::new(Length));
 
+        working_set.add_decl(Box::new(Ls));
+
+        working_set.add_decl(Box::new(Table));
+
         let sig = Signature::build("exit");
         working_set.add_decl(sig.predeclare());
         let sig = Signature::build("vars");

crates/nu-command/src/if_.rs

@@ -11,7 +11,7 @@ impl Command for If {
     }
 
     fn usage(&self) -> &str {
-        "Create a variable and give it a value."
+        "Conditionally run a block."
     }
 
     fn signature(&self) -> nu_protocol::Signature {

crates/nu-command/src/lib.rs

@@ -10,6 +10,9 @@ mod if_;
 mod length;
 mod let_;
 mod let_env;
+mod ls;
+mod table;
+mod where_;
 
 pub use alias::Alias;
 pub use benchmark::Benchmark;
@@ -23,3 +26,5 @@ pub use if_::If;
 pub use length::Length;
 pub use let_::Let;
 pub use let_env::LetEnv;
+pub use ls::Ls;
+pub use table::Table;

crates/nu-command/src/ls.rs

@@ -0,0 +1,93 @@
+use nu_engine::eval_expression;
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EvaluationContext};
+use nu_protocol::{IntoValueStream, Signature, SyntaxShape, Value};
+
+pub struct Ls;
+
+//NOTE: this is not a real implementation :D. It's just a simple one to test with until we port the real one.
+impl Command for Ls {
+    fn name(&self) -> &str {
+        "ls"
+    }
+
+    fn usage(&self) -> &str {
+        "List the files in a directory."
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("ls").optional(
+            "pattern",
+            SyntaxShape::GlobPattern,
+            "the glob pattern to use",
+        )
+    }
+
+    fn run(
+        &self,
+        context: &EvaluationContext,
+        call: &Call,
+        _input: Value,
+    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
+        let pattern = if let Some(expr) = call.positional.get(0) {
+            let result = eval_expression(context, expr)?;
+            result.as_string()?
+        } else {
+            "*".into()
+        };
+
+        let call_span = call.head;
+        let glob = glob::glob(&pattern).unwrap();
+
+        Ok(Value::Stream {
+            stream: glob
+                .into_iter()
+                .map(move |x| match x {
+                    Ok(path) => match std::fs::symlink_metadata(&path) {
+                        Ok(metadata) => {
+                            let is_file = metadata.is_file();
+                            let is_dir = metadata.is_dir();
+                            let filesize = metadata.len();
+
+                            Value::Record {
+                                cols: vec!["name".into(), "type".into(), "size".into()],
+                                vals: vec![
+                                    Value::String {
+                                        val: path.to_string_lossy().to_string(),
+                                        span: call_span,
+                                    },
+                                    if is_file {
+                                        Value::string("file", call_span)
+                                    } else if is_dir {
+                                        Value::string("dir", call_span)
+                                    } else {
+                                        Value::Nothing { span: call_span }
+                                    },
+                                    Value::Int {
+                                        val: filesize as i64,
+                                        span: call_span,
+                                    },
+                                ],
+                                span: call_span,
+                            }
+                        }
+                        Err(_) => Value::Record {
+                            cols: vec!["name".into(), "type".into(), "size".into()],
+                            vals: vec![
+                                Value::String {
+                                    val: path.to_string_lossy().to_string(),
+                                    span: call_span,
+                                },
+                                Value::Nothing { span: call_span },
+                                Value::Nothing { span: call_span },
+                            ],
+                            span: call_span,
+                        },
+                    },
+                    _ => Value::Nothing { span: call_span },
+                })
+                .into_value_stream(),
+            span: call_span,
+        })
+    }
+}

crates/nu-command/src/table.rs

@@ -0,0 +1,125 @@
+use std::collections::HashMap;
+
+use nu_protocol::ast::{Call, PathMember};
+use nu_protocol::engine::{Command, EvaluationContext};
+use nu_protocol::{Signature, Span, Value};
+use nu_table::StyledString;
+
+pub struct Table;
+
+//NOTE: this is not a real implementation :D. It's just a simple one to test with until we port the real one.
+impl Command for Table {
+    fn name(&self) -> &str {
+        "table"
+    }
+
+    fn usage(&self) -> &str {
+        "Render the table."
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("table")
+    }
+
+    fn run(
+        &self,
+        _context: &EvaluationContext,
+        call: &Call,
+        input: Value,
+    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
+        match input {
+            Value::List { vals, .. } => {
+                let table = convert_to_table(vals);
+
+                if let Some(table) = table {
+                    let result = nu_table::draw_table(&table, 80, &HashMap::new());
+
+                    Ok(Value::String {
+                        val: result,
+                        span: call.head,
+                    })
+                } else {
+                    Ok(Value::Nothing { span: call.head })
+                }
+            }
+            Value::Stream { stream, .. } => {
+                let table = convert_to_table(stream);
+
+                if let Some(table) = table {
+                    let result = nu_table::draw_table(&table, 80, &HashMap::new());
+
+                    Ok(Value::String {
+                        val: result,
+                        span: call.head,
+                    })
+                } else {
+                    Ok(Value::Nothing { span: call.head })
+                }
+            }
+            x => Ok(x),
+        }
+    }
+}
+
+fn convert_to_table(iter: impl IntoIterator<Item = Value>) -> Option<nu_table::Table> {
+    let mut iter = iter.into_iter().peekable();
+
+    if let Some(first) = iter.peek() {
+        let mut headers = first.columns();
+        headers.insert(0, "#".into());
+
+        let mut data = vec![];
+
+        for (row_num, item) in iter.enumerate() {
+            let mut row = vec![row_num.to_string()];
+
+            for header in headers.iter().skip(1) {
+                let result = item.clone().follow_cell_path(&[PathMember::String {
+                    val: header.into(),
+                    span: Span::unknown(),
+                }]);
+
+                match result {
+                    Ok(value) => row.push(value.into_string()),
+                    Err(_) => row.push(String::new()),
+                }
+            }
+
+            data.push(row);
+        }
+
+        Some(nu_table::Table {
+            headers: headers
+                .into_iter()
+                .map(|x| StyledString {
+                    contents: x,
+                    style: nu_table::TextStyle::default_header(),
+                })
+                .collect(),
+            data: data
+                .into_iter()
+                .map(|x| {
+                    x.into_iter()
+                        .enumerate()
+                        .map(|(col, y)| {
+                            if col == 0 {
+                                StyledString {
+                                    contents: y,
+                                    style: nu_table::TextStyle::default_header(),
+                                }
+                            } else {
+                                StyledString {
+                                    contents: y,
+                                    style: nu_table::TextStyle::basic_left(),
+                                }
+                            }
+                        })
+                        .collect::<Vec<StyledString>>()
+                })
+                .collect(),
+            theme: nu_table::Theme::rounded(),
+        })
+    } else {
+        None
+    }
+}

crates/nu-command/src/where_.rs

@@ -0,0 +1,92 @@
+use nu_engine::eval_expression;
+use nu_protocol::ast::{Call, Expr, Expression};
+use nu_protocol::engine::{Command, EvaluationContext};
+use nu_protocol::{IntoValueStream, ShellError, Signature, SyntaxShape, Value};
+
+pub struct Where;
+
+impl Command for Where {
+    fn name(&self) -> &str {
+        "where"
+    }
+
+    fn usage(&self) -> &str {
+        "Filter values based on a condition."
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("where").required("cond", SyntaxShape::RowCondition, "condition")
+    }
+
+    fn run(
+        &self,
+        context: &EvaluationContext,
+        call: &Call,
+        input: Value,
+    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
+        let cond = call.positional[0].clone();
+
+        let context = context.enter_scope();
+
+        let (var_id, cond) = match cond {
+            Expression {
+                expr: Expr::RowCondition(var_id, expr),
+                ..
+            } => (var_id, expr),
+            _ => return Err(ShellError::InternalError("Expected row condition".into())),
+        };
+
+        match input {
+            Value::Stream { stream, span } => {
+                let output_stream = stream
+                    .filter(move |value| {
+                        context.add_var(var_id, value.clone());
+
+                        let result = eval_expression(&context, &cond);
+
+                        match result {
+                            Ok(result) => result.is_true(),
+                            _ => false,
+                        }
+                    })
+                    .into_value_stream();
+
+                Ok(Value::Stream {
+                    stream: output_stream,
+                    span,
+                })
+            }
+            Value::List { vals, span } => {
+                let output_stream = vals
+                    .into_iter()
+                    .filter(move |value| {
+                        context.add_var(var_id, value.clone());
+
+                        let result = eval_expression(&context, &cond);
+
+                        match result {
+                            Ok(result) => result.is_true(),
+                            _ => false,
+                        }
+                    })
+                    .into_value_stream();
+
+                Ok(Value::Stream {
+                    stream: output_stream,
+                    span,
+                })
+            }
+            x => {
+                context.add_var(var_id, x.clone());
+
+                let result = eval_expression(&context, &cond)?;
+
+                if result.is_true() {
+                    Ok(x)
+                } else {
+                    Ok(Value::Nothing { span: call.head })
+                }
+            }
+        }
+    }
+}

crates/nu-engine/src/eval.rs

@@ -135,6 +135,7 @@ pub fn eval_expression(
 
             value.follow_cell_path(&column_path.tail)
         }
+        Expr::RowCondition(_, expr) => eval_expression(context, expr),
         Expr::Call(call) => eval_call(context, call, Value::nothing()),
         Expr::ExternalCall(_, _) => Err(ShellError::ExternalNotSupported(expr.span)),
         Expr::Operator(_) => Ok(Value::Nothing { span: expr.span }),

crates/nu-parser/src/flatten.rs

@@ -114,6 +114,7 @@ pub fn flatten_expression(
         Expr::String(_) => {
             vec![(expr.span, FlatShape::String)]
         }
+        Expr::RowCondition(_, expr) => flatten_expression(working_set, expr),
         Expr::Subexpression(block_id) => {
             flatten_block(working_set, working_set.get_block(*block_id))
         }

crates/nu-parser/src/parser.rs

@@ -871,7 +871,7 @@ pub(crate) fn parse_dollar_expr(
     } else if let (expr, None) = parse_range(working_set, span) {
         (expr, None)
     } else {
-        parse_full_column_path(working_set, span)
+        parse_full_column_path(working_set, None, span)
     }
 }
 
@@ -942,7 +942,7 @@ pub fn parse_string_interpolation(
                             end: b + 1,
                         };
 
-                        let (expr, err) = parse_full_column_path(working_set, span);
+                        let (expr, err) = parse_full_column_path(working_set, None, span);
                         error = error.or(err);
                         output.push(expr);
                     }
@@ -977,7 +977,7 @@ pub fn parse_string_interpolation(
                     end,
                 };
 
-                let (expr, err) = parse_full_column_path(working_set, span);
+                let (expr, err) = parse_full_column_path(working_set, None, span);
                 error = error.or(err);
                 output.push(expr);
             }
@@ -1067,6 +1067,7 @@ pub fn parse_variable_expr(
 
 pub fn parse_full_column_path(
     working_set: &mut StateWorkingSet,
+    implicit_head: Option<VarId>,
     span: Span,
 ) -> (Expression, Option<ParseError>) {
     // FIXME: assume for now a paren expr, but needs more
@@ -1077,10 +1078,10 @@ pub fn parse_full_column_path(
     let (tokens, err) = lex(source, span.start, &[b'\n'], &[b'.']);
     error = error.or(err);
 
-    let mut tokens = tokens.into_iter();
-    if let Some(head) = tokens.next() {
+    let mut tokens = tokens.into_iter().peekable();
+    if let Some(head) = tokens.peek() {
         let bytes = working_set.get_span_contents(head.span);
-        let head = if bytes.starts_with(b"(") {
+        let (head, mut expect_dot) = if bytes.starts_with(b"(") {
             let mut start = head.span.start;
             let mut end = head.span.end;
 
@@ -1105,27 +1106,42 @@ pub fn parse_full_column_path(
 
             let source = working_set.get_span_contents(span);
 
-            let (tokens, err) = lex(source, span.start, &[b'\n'], &[]);
+            let (output, err) = lex(source, span.start, &[b'\n'], &[]);
             error = error.or(err);
 
-            let (output, err) = lite_parse(&tokens);
+            let (output, err) = lite_parse(&output);
             error = error.or(err);
 
             let (output, err) = parse_block(working_set, &output, true);
             error = error.or(err);
 
             let block_id = working_set.add_block(output);
+            tokens.next();
 
-            Expression {
-                expr: Expr::Subexpression(block_id),
-                span,
-                ty: Type::Unknown, // FIXME
-            }
+            (
+                Expression {
+                    expr: Expr::Subexpression(block_id),
+                    span,
+                    ty: Type::Unknown, // FIXME
+                },
+                true,
+            )
         } else if bytes.starts_with(b"$") {
             let (out, err) = parse_variable_expr(working_set, head.span);
             error = error.or(err);
 
-            out
+            tokens.next();
+
+            (out, true)
+        } else if let Some(var_id) = implicit_head {
+            (
+                Expression {
+                    expr: Expr::Var(var_id),
+                    span: Span::unknown(),
+                    ty: Type::Unknown,
+                },
+                false,
+            )
         } else {
             return (
                 garbage(span),
@@ -1139,7 +1155,6 @@ pub fn parse_full_column_path(
 
         let mut tail = vec![];
 
-        let mut expect_dot = true;
         for path_element in tokens {
             let bytes = working_set.get_span_contents(path_element.span);
 
@@ -1313,11 +1328,40 @@ pub fn parse_var_with_opt_type(
         )
     }
 }
+
+pub fn expand_to_cell_path(
+    working_set: &mut StateWorkingSet,
+    expression: &mut Expression,
+    var_id: VarId,
+) {
+    if let Expression {
+        expr: Expr::String(_),
+        span,
+        ..
+    } = expression
+    {
+        // Re-parse the string as if it were a cell-path
+        let (new_expression, _err) = parse_full_column_path(working_set, Some(var_id), *span);
+
+        *expression = new_expression;
+    }
+}
+
 pub fn parse_row_condition(
     working_set: &mut StateWorkingSet,
     spans: &[Span],
 ) -> (Expression, Option<ParseError>) {
-    parse_math_expression(working_set, spans)
+    let var_id = working_set.add_variable(b"$it".to_vec(), Type::Unknown);
+    let (expression, err) = parse_math_expression(working_set, spans, Some(var_id));
+    let span = span(spans);
+    (
+        Expression {
+            ty: Type::Bool,
+            span,
+            expr: Expr::RowCondition(var_id, Box::new(expression)),
+        },
+        err,
+    )
 }
 
 pub fn parse_signature(
@@ -2015,7 +2059,7 @@ pub fn parse_value(
         if let (expr, None) = parse_range(working_set, span) {
             return (expr, None);
         } else {
-            return parse_full_column_path(working_set, span);
+            return parse_full_column_path(working_set, None, span);
         }
     } else if bytes.starts_with(b"{") {
         if matches!(shape, SyntaxShape::Block) || matches!(shape, SyntaxShape::Any) {
@@ -2162,6 +2206,7 @@ pub fn parse_operator(
 pub fn parse_math_expression(
     working_set: &mut StateWorkingSet,
     spans: &[Span],
+    lhs_row_var_id: Option<VarId>,
 ) -> (Expression, Option<ParseError>) {
     // As the expr_stack grows, we increase the required precedence to grow larger
     // If, at any time, the operator we're looking at is the same or lower precedence
@@ -2220,6 +2265,10 @@ pub fn parse_math_expression(
                     .pop()
                     .expect("internal error: expression stack empty");
 
+                if let Some(row_var_id) = lhs_row_var_id {
+                    expand_to_cell_path(working_set, &mut lhs, row_var_id);
+                }
+
                 let (result_ty, err) = math_result_type(working_set, &mut lhs, &mut op, &mut rhs);
                 error = error.or(err);
 
@@ -2250,6 +2299,10 @@ pub fn parse_math_expression(
             .pop()
             .expect("internal error: expression stack empty");
 
+        if let Some(row_var_id) = lhs_row_var_id {
+            expand_to_cell_path(working_set, &mut lhs, row_var_id);
+        }
+
         let (result_ty, err) = math_result_type(working_set, &mut lhs, &mut op, &mut rhs);
         error = error.or(err);
 
@@ -2276,7 +2329,7 @@ pub fn parse_expression(
 
     match bytes[0] {
         b'0' | b'1' | b'2' | b'3' | b'4' | b'5' | b'6' | b'7' | b'8' | b'9' | b'(' | b'{'
-        | b'[' | b'$' | b'"' | b'\'' | b'-' => parse_math_expression(working_set, spans),
+        | b'[' | b'$' | b'"' | b'\'' | b'-' => parse_math_expression(working_set, spans, None),
         _ => parse_call(working_set, spans, true),
     }
 }

crates/nu-protocol/src/ast/expr.rs

@@ -15,6 +15,7 @@ pub enum Expr {
     Call(Box<Call>),
     ExternalCall(Vec<u8>, Vec<Vec<u8>>),
     Operator(Operator),
+    RowCondition(VarId, Box<Expression>),
     BinaryOp(Box<Expression>, Box<Expression>, Box<Expression>), //lhs, op, rhs
     Subexpression(BlockId),
     Block(BlockId),

crates/nu-protocol/src/engine/engine_state.rs

@@ -123,6 +123,24 @@ impl EngineState {
         None
     }
 
+    pub fn find_commands_by_prefix(&self, name: &[u8]) -> Vec<Vec<u8>> {
+        let mut output = vec![];
+
+        for scope in self.scope.iter().rev() {
+            for decl in &scope.decls {
+                if decl.0.starts_with(name) {
+                    output.push(decl.0.clone());
+                }
+            }
+        }
+
+        output
+    }
+
+    pub fn get_span_contents(&self, span: Span) -> &[u8] {
+        &self.file_contents[span.start..span.end]
+    }
+
     pub fn get_var(&self, var_id: VarId) -> &Type {
         self.vars
             .get(var_id)
@@ -496,6 +514,24 @@ impl<'a> StateWorkingSet<'a> {
         }
     }
 
+    pub fn find_commands_by_prefix(&self, name: &[u8]) -> Vec<Vec<u8>> {
+        let mut output = vec![];
+
+        for scope in self.delta.scope.iter().rev() {
+            for decl in &scope.decls {
+                if decl.0.starts_with(name) {
+                    output.push(decl.0.clone());
+                }
+            }
+        }
+
+        let mut permanent = self.permanent_state.find_commands_by_prefix(name);
+
+        output.append(&mut permanent);
+
+        output
+    }
+
     pub fn get_block(&self, block_id: BlockId) -> &Block {
         let num_permanent_blocks = self.permanent_state.num_blocks();
         if block_id < num_permanent_blocks {

crates/nu-protocol/src/value/mod.rs

@@ -277,6 +277,24 @@ impl Value {
 
         Ok(current)
     }
+
+    pub fn string(s: &str, span: Span) -> Value {
+        Value::String {
+            val: s.into(),
+            span,
+        }
+    }
+
+    pub fn is_true(&self) -> bool {
+        matches!(self, Value::Bool { val: true, .. })
+    }
+
+    pub fn columns(&self) -> Vec<String> {
+        match self {
+            Value::Record { cols, .. } => cols.clone(),
+            _ => vec![],
+        }
+    }
 }
 
 impl PartialEq for Value {

crates/nu-table/.gitignore

@@ -0,0 +1,22 @@
+/target
+/scratch
+**/*.rs.bk
+history.txt
+tests/fixtures/nuplayground
+crates/*/target
+
+# Debian/Ubuntu
+debian/.debhelper/
+debian/debhelper-build-stamp
+debian/files
+debian/nu.substvars
+debian/nu/
+
+# macOS junk
+.DS_Store
+
+# JetBrains' IDE items
+.idea/*
+
+# VSCode's IDE items
+.vscode/*

crates/nu-table/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+authors = ["The Nu Project Contributors"]
+description = "Nushell table printing"
+edition = "2018"
+license = "MIT"
+name = "nu-table"
+version = "0.36.0"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[[bin]]
+name = "table"
+path = "src/main.rs"
+
+[dependencies]
+nu-ansi-term = "0.36.0"
+
+regex = "1.4"
+unicode-width = "0.1.8"

crates/nu-table/src/lib.rs

@@ -0,0 +1,5 @@
+mod table;
+mod wrap;
+
+pub use table::{draw_table, StyledString, Table, TextStyle, Theme};
+pub use wrap::Alignment;

crates/nu-table/src/main.rs

@@ -0,0 +1,86 @@
+use nu_table::{draw_table, StyledString, Table, TextStyle, Theme};
+use std::collections::HashMap;
+
+fn main() {
+    let args: Vec<_> = std::env::args().collect();
+    let mut width = 0;
+
+    if args.len() > 1 {
+        // Width in terminal characters
+        width = args[1].parse::<usize>().expect("Need a width in columns");
+    }
+
+    if width < 4 {
+        println!("Width must be greater than or equal to 4, setting width to 80");
+        width = 80;
+    }
+
+    // The mocked up table data
+    let (table_headers, row_data) = make_table_data();
+    // The table headers
+    let headers = vec_of_str_to_vec_of_styledstr(&table_headers, true);
+    // The table rows
+    let rows = vec_of_str_to_vec_of_styledstr(&row_data, false);
+    // The table itself
+    let table = Table::new(headers, vec![rows; 3], Theme::rounded());
+    // FIXME: Config isn't available from here so just put these here to compile
+    let color_hm: HashMap<String, nu_ansi_term::Style> = HashMap::new();
+    // Capture the table as a string
+    let output_table = draw_table(&table, width, &color_hm);
+    // Draw the table
+    println!("{}", output_table)
+}
+
+fn make_table_data() -> (Vec<&'static str>, Vec<&'static str>) {
+    let table_headers = vec![
+        "category",
+        "description",
+        "emoji",
+        "ios_version",
+        "unicode_version",
+        "aliases",
+        "tags",
+        "category2",
+        "description2",
+        "emoji2",
+        "ios_version2",
+        "unicode_version2",
+        "aliases2",
+        "tags2",
+    ];
+
+    let row_data = vec![
+        "Smileys & Emotion",
+        "grinning face",
+        "😀",
+        "6",
+        "6.1",
+        "grinning",
+        "smile",
+        "Smileys & Emotion",
+        "grinning face",
+        "😀",
+        "6",
+        "6.1",
+        "grinning",
+        "smile",
+    ];
+
+    (table_headers, row_data)
+}
+
+fn vec_of_str_to_vec_of_styledstr(data: &[&str], is_header: bool) -> Vec<StyledString> {
+    let mut v = vec![];
+
+    for x in data {
+        if is_header {
+            v.push(StyledString::new(
+                String::from(*x),
+                TextStyle::default_header(),
+            ))
+        } else {
+            v.push(StyledString::new(String::from(*x), TextStyle::basic_left()))
+        }
+    }
+    v
+}

crates/nu-table/src/wrap.rs

@@ -0,0 +1,274 @@
+use crate::table::TextStyle;
+use nu_ansi_term::Style;
+use std::collections::HashMap;
+use std::{fmt::Display, iter::Iterator};
+use unicode_width::UnicodeWidthStr;
+
+#[derive(Debug, Clone, Copy)]
+pub enum Alignment {
+    Left,
+    Center,
+    Right,
+}
+
+#[derive(Debug)]
+pub struct Subline<'a> {
+    pub subline: &'a str,
+    pub width: usize,
+}
+
+#[derive(Debug)]
+pub struct Line<'a> {
+    pub sublines: Vec<Subline<'a>>,
+    pub width: usize,
+}
+
+#[derive(Debug)]
+pub struct WrappedLine {
+    pub line: String,
+    pub width: usize,
+}
+
+#[derive(Debug)]
+pub struct WrappedCell {
+    pub lines: Vec<WrappedLine>,
+    pub max_width: usize,
+
+    pub style: TextStyle,
+}
+
+impl<'a> Display for Line<'a> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let mut first = true;
+        for subline in &self.sublines {
+            if !first {
+                write!(f, " ")?;
+            } else {
+                first = false;
+            }
+            write!(f, "{}", subline.subline)?;
+        }
+        Ok(())
+    }
+}
+
+pub fn split_sublines(input: &str) -> Vec<Vec<Subline>> {
+    input
+        .split_terminator('\n')
+        .map(|line| {
+            line.split_terminator(' ')
+                .map(|x| Subline {
+                    subline: x,
+                    width: {
+                        // We've tried UnicodeWidthStr::width(x), UnicodeSegmentation::graphemes(x, true).count()
+                        // and x.chars().count() with all types of combinations. Currently, it appears that
+                        // getting the max of char count and Unicode width seems to produce the best layout.
+                        // However, it's not perfect.
+                        let c = x.chars().count();
+                        let u = UnicodeWidthStr::width(x);
+                        std::cmp::max(c, u)
+                    },
+                })
+                .collect::<Vec<_>>()
+        })
+        .collect::<Vec<_>>()
+}
+
+pub fn column_width(input: &[Vec<Subline>]) -> usize {
+    let mut max = 0;
+
+    for line in input {
+        let mut total = 0;
+
+        let mut first = true;
+        for inp in line {
+            if !first {
+                // Account for the space
+                total += 1;
+            } else {
+                first = false;
+            }
+
+            total += inp.width;
+        }
+
+        if total > max {
+            max = total;
+        }
+    }
+
+    max
+}
+
+fn split_word(cell_width: usize, word: &str) -> Vec<Subline> {
+    use unicode_width::UnicodeWidthChar;
+
+    let mut output = vec![];
+    let mut current_width = 0;
+    let mut start_index = 0;
+    let mut end_index;
+
+    for c in word.char_indices() {
+        if let Some(width) = c.1.width() {
+            end_index = c.0;
+            if current_width + width > cell_width {
+                output.push(Subline {
+                    subline: &word[start_index..end_index],
+                    width: current_width,
+                });
+
+                start_index = c.0;
+                current_width = width;
+            } else {
+                current_width += width;
+            }
+        }
+    }
+
+    if start_index != word.len() {
+        output.push(Subline {
+            subline: &word[start_index..],
+            width: current_width,
+        });
+    }
+
+    output
+}
+
+pub fn wrap<'a>(
+    cell_width: usize,
+    mut input: impl Iterator<Item = Subline<'a>>,
+    color_hm: &HashMap<String, Style>,
+    re_leading: &regex::Regex,
+    re_trailing: &regex::Regex,
+) -> (Vec<WrappedLine>, usize) {
+    let mut lines = vec![];
+    let mut current_line: Vec<Subline> = vec![];
+    let mut current_width = 0;
+    let mut first = true;
+    let mut max_width = 0;
+    let lead_trail_space_bg_color = color_hm
+        .get("leading_trailing_space_bg")
+        .unwrap_or(&Style::default())
+        .to_owned();
+
+    loop {
+        match input.next() {
+            Some(item) => {
+                if !first {
+                    current_width += 1;
+                } else {
+                    first = false;
+                }
+
+                if item.width + current_width > cell_width {
+                    // If this is a really long single word, we need to split the word
+                    if current_line.len() == 1 && current_width > cell_width {
+                        max_width = cell_width;
+                        let sublines = split_word(cell_width, current_line[0].subline);
+                        for subline in sublines {
+                            let width = subline.width;
+                            lines.push(Line {
+                                sublines: vec![subline],
+                                width,
+                            });
+                        }
+
+                        first = true;
+
+                        current_width = item.width;
+                        current_line = vec![item];
+                    } else {
+                        if !current_line.is_empty() {
+                            lines.push(Line {
+                                sublines: current_line,
+                                width: current_width,
+                            });
+                        }
+
+                        first = true;
+
+                        current_width = item.width;
+                        current_line = vec![item];
+                        max_width = std::cmp::max(max_width, current_width);
+                    }
+                } else {
+                    current_width += item.width;
+                    current_line.push(item);
+                }
+            }
+            None => {
+                if current_width > cell_width {
+                    // We need to break up the last word
+                    let sublines = split_word(cell_width, current_line[0].subline);
+                    for subline in sublines {
+                        let width = subline.width;
+                        lines.push(Line {
+                            sublines: vec![subline],
+                            width,
+                        });
+                    }
+                } else if current_width > 0 {
+                    lines.push(Line {
+                        sublines: current_line,
+                        width: current_width,
+                    });
+                }
+                break;
+            }
+        }
+    }
+
+    let mut current_max = 0;
+    let mut output = vec![];
+
+    for line in lines {
+        let mut current_line_width = 0;
+        let mut first = true;
+        let mut current_line = String::new();
+
+        for subline in line.sublines {
+            if !first {
+                current_line_width += 1 + subline.width;
+                current_line.push(' ');
+            } else {
+                first = false;
+                current_line_width = subline.width;
+            }
+            current_line.push_str(subline.subline);
+        }
+
+        if current_line_width > current_max {
+            current_max = current_line_width;
+        }
+
+        // highlight leading and trailing spaces so they stand out.
+        let mut bg_color_string = Style::default().prefix().to_string();
+        // right now config settings can only set foreground colors so, in this
+        // instance we take the foreground color and make it a background color
+        if let Some(bg) = lead_trail_space_bg_color.foreground {
+            bg_color_string = Style::default().on(bg).prefix().to_string()
+        };
+
+        if let Some(leading_match) = re_leading.find(&current_line.clone()) {
+            String::insert_str(
+                &mut current_line,
+                leading_match.end(),
+                nu_ansi_term::ansi::RESET,
+            );
+            String::insert_str(&mut current_line, leading_match.start(), &bg_color_string);
+        }
+
+        if let Some(trailing_match) = re_trailing.find(&current_line.clone()) {
+            String::insert_str(&mut current_line, trailing_match.start(), &bg_color_string);
+            current_line += nu_ansi_term::ansi::RESET;
+        }
+
+        output.push(WrappedLine {
+            line: current_line,
+            width: current_line_width,
+        });
+    }
+
+    (output, current_max)
+}

src/main.rs

@@ -1,4 +1,4 @@
-use nu_cli::{report_parsing_error, report_shell_error, NuHighlighter};
+use nu_cli::{report_parsing_error, report_shell_error, NuCompleter, NuHighlighter};
 use nu_command::create_default_context;
 use nu_engine::eval_block;
 use nu_parser::parse;
@@ -6,6 +6,7 @@ use nu_protocol::{
     engine::{EngineState, EvaluationContext, StateWorkingSet},
     Value,
 };
+use reedline::DefaultCompletionActionHandler;
 
 #[cfg(test)]
 mod tests;
@@ -53,6 +54,8 @@ fn main() -> std::io::Result<()> {
     } else {
         use reedline::{DefaultPrompt, FileBackedHistory, Reedline, Signal};
 
+        let completer = NuCompleter::new(engine_state.clone());
+
         let mut line_editor = Reedline::create()?
             .with_history(Box::new(FileBackedHistory::with_file(
                 1000,
@@ -60,7 +63,10 @@ fn main() -> std::io::Result<()> {
             )?))?
             .with_highlighter(Box::new(NuHighlighter {
                 engine_state: engine_state.clone(),
-            }));
+            }))
+            .with_completion_action_handler(Box::new(
+                DefaultCompletionActionHandler::default().with_completer(Box::new(completer)),
+            ));
 
         let prompt = DefaultPrompt::new(1);
         let mut current_line = 1;

src/tests.rs

@@ -292,3 +292,19 @@ fn row_iteration() -> TestResult {
 fn record_iteration() -> TestResult {
     run_test("([[name, level]; [aa, 100], [bb, 200]] | each { $it | each { |x| if $x.column == \"level\" { $x.value + 100 } else { $x.value } } }).level", "[200, 300]")
 }
+
+#[test]
+fn row_condition1() -> TestResult {
+    run_test(
+        "([[name, size]; [a, 1], [b, 2], [c, 3]] | where size < 3).name",
+        "[a, b]",
+    )
+}
+
+#[test]
+fn row_condition2() -> TestResult {
+    run_test(
+        "[[name, size]; [a, 1], [b, 2], [c, 3]] | where $it.size > 2 | length",
+        "1",
+    )
+}