Add cell paths

crates/nu-cli/src/errors.rs

@@ -328,6 +328,40 @@ pub fn report_shell_error(
                         Label::primary(diag_file_id, diag_range).with_message("division by zero")
                     ])
             }
+            ShellError::AccessBeyondEnd(len, span) => {
+                let (diag_file_id, diag_range) = convert_span_to_diag(working_set, span)?;
+
+                Diagnostic::error()
+                    .with_message("Row number too large")
+                    .with_labels(vec![Label::primary(diag_file_id, diag_range)
+                        .with_message(format!("row number too large (max: {})", *len))])
+            }
+            ShellError::AccessBeyondEndOfStream(span) => {
+                let (diag_file_id, diag_range) = convert_span_to_diag(working_set, span)?;
+
+                Diagnostic::error()
+                    .with_message("Row number too large")
+                    .with_labels(vec![Label::primary(diag_file_id, diag_range)
+                        .with_message("row number too large")])
+            }
+            ShellError::IncompatiblePathAccess(name, span) => {
+                let (diag_file_id, diag_range) = convert_span_to_diag(working_set, span)?;
+
+                Diagnostic::error()
+                    .with_message("Data cannot be accessed with a column path")
+                    .with_labels(vec![Label::primary(diag_file_id, diag_range)
+                        .with_message(format!("{} doesn't support column paths", name))])
+            }
+            ShellError::CantFindColumn(span) => {
+                let (diag_file_id, diag_range) = convert_span_to_diag(working_set, span)?;
+
+                //FIXME: add "did you mean"
+                Diagnostic::error()
+                    .with_message("Cannot find column")
+                    .with_labels(vec![
+                        Label::primary(diag_file_id, diag_range).with_message("cannot find column")
+                    ])
+            }
         };
 
     // println!("DIAG");

crates/nu-engine/src/eval.rs

@@ -102,6 +102,11 @@ pub fn eval_expression(
         Expr::Var(var_id) => context
             .get_var(*var_id)
             .map_err(move |_| ShellError::VariableNotFoundAtRuntime(expr.span)),
+        Expr::FullCellPath(column_path) => {
+            let value = eval_expression(context, &column_path.head)?;
+
+            value.follow_column_path(&column_path.tail)
+        }
         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

@@ -1,4 +1,4 @@
-use nu_protocol::ast::{Block, Expr, Expression, Pipeline, Statement};
+use nu_protocol::ast::{Block, Expr, Expression, PathMember, Pipeline, Statement};
 use nu_protocol::{engine::StateWorkingSet, Span};
 
 #[derive(Debug)]
@@ -67,6 +67,17 @@ pub fn flatten_expression(
         Expr::Float(_) => {
             vec![(expr.span, FlatShape::Float)]
         }
+        Expr::FullCellPath(column_path) => {
+            let mut output = vec![];
+            output.extend(flatten_expression(working_set, &column_path.head));
+            for path_element in &column_path.tail {
+                match path_element {
+                    PathMember::String { span, .. } => output.push((*span, FlatShape::String)),
+                    PathMember::Int { span, .. } => output.push((*span, FlatShape::Int)),
+                }
+            }
+            output
+        }
         Expr::Range(from, to, op) => {
             let mut output = vec![];
             if let Some(f) = from {

crates/nu-parser/src/parser.rs

@@ -6,7 +6,8 @@ use crate::{
 
 use nu_protocol::{
     ast::{
-        Block, Call, Expr, Expression, Operator, Pipeline, RangeInclusion, RangeOperator, Statement,
+        Block, Call, Expr, Expression, FullCellPath, Operator, PathMember, Pipeline,
+        RangeInclusion, RangeOperator, Statement,
     },
     engine::StateWorkingSet,
     span, Flag, PositionalArg, Signature, Span, SyntaxShape, Type, VarId,
@@ -595,9 +596,9 @@ pub fn parse_call(
     }
 }
 
-pub fn parse_int(token: &str, span: Span) -> (Expression, Option<ParseError>) {
+pub fn parse_int(token: &[u8], span: Span) -> (Expression, Option<ParseError>) {
-    if let Some(token) = token.strip_prefix("0x") {
+    if let Some(token) = token.strip_prefix(b"0x") {
-        if let Ok(v) = i64::from_str_radix(token, 16) {
+        if let Ok(v) = i64::from_str_radix(&String::from_utf8_lossy(token), 16) {
             (
                 Expression {
                     expr: Expr::Int(v),
@@ -616,8 +617,8 @@ pub fn parse_int(token: &str, span: Span) -> (Expression, Option<ParseError>) {
                 )),
             )
         }
-    } else if let Some(token) = token.strip_prefix("0b") {
+    } else if let Some(token) = token.strip_prefix(b"0b") {
-        if let Ok(v) = i64::from_str_radix(token, 2) {
+        if let Ok(v) = i64::from_str_radix(&String::from_utf8_lossy(token), 2) {
             (
                 Expression {
                     expr: Expr::Int(v),
@@ -636,8 +637,8 @@ pub fn parse_int(token: &str, span: Span) -> (Expression, Option<ParseError>) {
                 )),
             )
         }
-    } else if let Some(token) = token.strip_prefix("0o") {
+    } else if let Some(token) = token.strip_prefix(b"0o") {
-        if let Ok(v) = i64::from_str_radix(token, 8) {
+        if let Ok(v) = i64::from_str_radix(&String::from_utf8_lossy(token), 8) {
             (
                 Expression {
                     expr: Expr::Int(v),
@@ -656,7 +657,7 @@ pub fn parse_int(token: &str, span: Span) -> (Expression, Option<ParseError>) {
                 )),
             )
         }
-    } else if let Ok(x) = token.parse::<i64>() {
+    } else if let Ok(x) = String::from_utf8_lossy(token).parse::<i64>() {
         (
             Expression {
                 expr: Expr::Int(x),
@@ -673,8 +674,8 @@ pub fn parse_int(token: &str, span: Span) -> (Expression, Option<ParseError>) {
     }
 }
 
-pub fn parse_float(token: &str, span: Span) -> (Expression, Option<ParseError>) {
+pub fn parse_float(token: &[u8], span: Span) -> (Expression, Option<ParseError>) {
-    if let Ok(x) = token.parse::<f64>() {
+    if let Ok(x) = String::from_utf8_lossy(token).parse::<f64>() {
         (
             Expression {
                 expr: Expr::Float(x),
@@ -691,7 +692,7 @@ pub fn parse_float(token: &str, span: Span) -> (Expression, Option<ParseError>)
     }
 }
 
-pub fn parse_number(token: &str, span: Span) -> (Expression, Option<ParseError>) {
+pub fn parse_number(token: &[u8], span: Span) -> (Expression, Option<ParseError>) {
     if let (x, None) = parse_int(token, span) {
         (x, None)
     } else if let (x, None) = parse_float(token, span) {
@@ -850,7 +851,7 @@ pub(crate) fn parse_dollar_expr(
     } else if let (expr, None) = parse_range(working_set, span) {
         (expr, None)
     } else {
-        parse_variable_expr(working_set, span)
+        parse_full_column_path(working_set, span)
     }
 }
 
@@ -1049,11 +1050,19 @@ pub fn parse_full_column_path(
     span: Span,
 ) -> (Expression, Option<ParseError>) {
     // FIXME: assume for now a paren expr, but needs more
-    let bytes = working_set.get_span_contents(span);
+    let full_column_span = span;
+    let source = working_set.get_span_contents(span);
     let mut error = None;
 
-    let mut start = span.start;
+    let (tokens, err) = lex(source, span.start, &[b'\n'], &[b'.']);
-    let mut end = span.end;
+    error = error.or(err);
+
+    let mut tokens = tokens.into_iter();
+    if let Some(head) = tokens.next() {
+        let bytes = working_set.get_span_contents(head.span);
+        let head = if bytes.starts_with(b"(") {
+            let mut start = head.span.start;
+            let mut end = head.span.end;
 
             if bytes.starts_with(b"(") {
                 start += 1;
@@ -1076,10 +1085,10 @@ pub fn parse_full_column_path(
 
             let source = working_set.get_span_contents(span);
 
-    let (output, err) = lex(source, start, &[b'\n'], &[]);
+            let (tokens, err) = lex(source, span.start, &[b'\n'], &[]);
             error = error.or(err);
 
-    let (output, err) = lite_parse(&output);
+            let (output, err) = lite_parse(&tokens);
             error = error.or(err);
 
             let (output, err) = parse_block(working_set, &output, true);
@@ -1087,14 +1096,86 @@ pub fn parse_full_column_path(
 
             let block_id = working_set.add_block(output);
 
-    (
             Expression {
                 expr: Expr::Subexpression(block_id),
                 span,
                 ty: Type::Unknown, // FIXME
+            }
+        } else if bytes.starts_with(b"$") {
+            let (out, err) = parse_variable_expr(working_set, head.span);
+            error = error.or(err);
+
+            out
+        } else {
+            return (
+                garbage(span),
+                Some(ParseError::Mismatch(
+                    "variable or subexpression".into(),
+                    String::from_utf8_lossy(bytes).to_string(),
+                    span,
+                )),
+            );
+        };
+
+        let mut tail = vec![];
+
+        let mut expect_dot = true;
+        for path_element in tokens {
+            let bytes = working_set.get_span_contents(path_element.span);
+
+            if expect_dot {
+                expect_dot = false;
+                if bytes.len() != 1 || bytes[0] != b'.' {
+                    error =
+                        error.or_else(|| Some(ParseError::Expected('.'.into(), path_element.span)));
+                }
+            } else {
+                expect_dot = true;
+
+                match parse_int(bytes, path_element.span) {
+                    (
+                        Expression {
+                            expr: Expr::Int(val),
+                            span,
+                            ..
+                        },
+                        None,
+                    ) => tail.push(PathMember::Int {
+                        val: val as usize,
+                        span,
+                    }),
+                    _ => {
+                        let (result, err) = parse_string(working_set, path_element.span);
+                        error = error.or(err);
+                        match result {
+                            Expression {
+                                expr: Expr::String(string),
+                                span,
+                                ..
+                            } => {
+                                tail.push(PathMember::String { val: string, span });
+                            }
+                            _ => {
+                                error = error
+                                    .or_else(|| Some(ParseError::Expected("string".into(), span)));
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        (
+            Expression {
+                expr: Expr::FullCellPath(Box::new(FullCellPath { head, tail })),
+                ty: Type::Unknown,
+                span: full_column_span,
             },
             error,
         )
+    } else {
+        (garbage(span), error)
+    }
 }
 
 pub fn parse_string(
@@ -1136,7 +1217,7 @@ pub fn parse_shape_name(
     let result = match bytes {
         b"any" => SyntaxShape::Any,
         b"string" => SyntaxShape::String,
-        b"column-path" => SyntaxShape::ColumnPath,
+        b"cell-path" => SyntaxShape::CellPath,
         b"number" => SyntaxShape::Number,
         b"range" => SyntaxShape::Range,
         b"int" => SyntaxShape::Int,
@@ -1899,26 +1980,8 @@ pub fn parse_value(
     }
 
     match shape {
-        SyntaxShape::Number => {
+        SyntaxShape::Number => parse_number(bytes, span),
-            if let Ok(token) = String::from_utf8(bytes.into()) {
+        SyntaxShape::Int => parse_int(bytes, span),
-                parse_number(&token, span)
-            } else {
-                (
-                    garbage(span),
-                    Some(ParseError::Expected("number".into(), span)),
-                )
-            }
-        }
-        SyntaxShape::Int => {
-            if let Ok(token) = String::from_utf8(bytes.into()) {
-                parse_int(&token, span)
-            } else {
-                (
-                    garbage(span),
-                    Some(ParseError::Expected("int".into(), span)),
-                )
-            }
-        }
         SyntaxShape::Range => parse_range(working_set, span),
         SyntaxShape::String | SyntaxShape::GlobPattern | SyntaxShape::FilePath => {
             parse_string(working_set, span)

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

@@ -0,0 +1,19 @@
+use super::Expression;
+use crate::Span;
+
+#[derive(Debug, Clone)]
+pub enum PathMember {
+    String { val: String, span: Span },
+    Int { val: usize, span: Span },
+}
+
+#[derive(Debug, Clone)]
+pub struct CellPath {
+    pub members: Vec<PathMember>,
+}
+
+#[derive(Debug, Clone)]
+pub struct FullCellPath {
+    pub head: Expression,
+    pub tail: Vec<PathMember>,
+}

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

@@ -1,4 +1,4 @@
-use super::{Call, Expression, Operator, RangeOperator};
+use super::{Call, Expression, FullCellPath, Operator, RangeOperator};
 use crate::{BlockId, Signature, Span, VarId};
 
 #[derive(Debug, Clone)]
@@ -22,6 +22,7 @@ pub enum Expr {
     Table(Vec<Expression>, Vec<Vec<Expression>>),
     Keyword(Vec<u8>, Span, Box<Expression>),
     String(String), // FIXME: improve this in the future?
+    FullCellPath(Box<FullCellPath>),
     Signature(Box<Signature>),
     Garbage,
 }

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

@@ -1,5 +1,6 @@
 mod block;
 mod call;
+mod cell_path;
 mod expr;
 mod expression;
 mod operator;
@@ -8,6 +9,7 @@ mod statement;
 
 pub use block::*;
 pub use call::*;
+pub use cell_path::*;
 pub use expr::*;
 pub use expression::*;
 pub use operator::*;

crates/nu-protocol/src/shell_error.rs

@@ -17,4 +17,8 @@ pub enum ShellError {
     CantConvert(String, Span),
     DivisionByZero(Span),
     CannotCreateRange(Span),
+    AccessBeyondEnd(usize, Span),
+    AccessBeyondEndOfStream(Span),
+    IncompatiblePathAccess(String, Span),
+    CantFindColumn(Span),
 }

crates/nu-protocol/src/syntax_shape.rs

@@ -13,10 +13,10 @@ pub enum SyntaxShape {
     String,
 
     /// A dotted path to navigate the table
-    ColumnPath,
+    CellPath,
 
     /// A dotted path to navigate the table (including variable)
-    FullColumnPath,
+    FullCellPath,
 
     /// Only a numeric (integer or decimal) value is allowed
     Number,
@@ -76,12 +76,12 @@ impl SyntaxShape {
         match self {
             SyntaxShape::Any => Type::Unknown,
             SyntaxShape::Block => Type::Block,
-            SyntaxShape::ColumnPath => Type::Unknown,
+            SyntaxShape::CellPath => Type::Unknown,
             SyntaxShape::Duration => Type::Duration,
             SyntaxShape::Expression => Type::Unknown,
             SyntaxShape::FilePath => Type::FilePath,
             SyntaxShape::Filesize => Type::Filesize,
-            SyntaxShape::FullColumnPath => Type::Unknown,
+            SyntaxShape::FullCellPath => Type::Unknown,
             SyntaxShape::GlobPattern => Type::String,
             SyntaxShape::Int => Type::Int,
             SyntaxShape::List(x) => {

crates/nu-protocol/src/ty.rs

@@ -8,7 +8,7 @@ pub enum Type {
     Bool,
     String,
     Block,
-    ColumnPath,
+    CellPath,
     Duration,
     FilePath,
     Filesize,
@@ -27,7 +27,7 @@ impl Display for Type {
         match self {
             Type::Block => write!(f, "block"),
             Type::Bool => write!(f, "bool"),
-            Type::ColumnPath => write!(f, "column path"),
+            Type::CellPath => write!(f, "cell path"),
             Type::Duration => write!(f, "duration"),
             Type::FilePath => write!(f, "filepath"),
             Type::Filesize => write!(f, "filesize"),

crates/nu-protocol/src/value.rs

@@ -1,6 +1,6 @@
 use std::{cell::RefCell, fmt::Debug, rc::Rc};
 
-use crate::ast::RangeInclusion;
+use crate::ast::{PathMember, RangeInclusion};
 use crate::{span, BlockId, Span, Type};
 
 use crate::ShellError;
@@ -364,13 +364,17 @@ impl Value {
             }
             Value::String { val, .. } => val,
             Value::ValueStream { stream, .. } => stream.into_string(),
-            Value::List { val, .. } => val
+            Value::List { val, .. } => format!(
-                .into_iter()
+                "[{}]",
+                val.into_iter()
                     .map(|x| x.into_string())
                     .collect::<Vec<_>>()
-                .join(", "),
+                    .join(", ")
-            Value::Table { val, .. } => val
+            ),
-                .into_iter()
+            Value::Table { val, headers, .. } => format!(
+                "[= {} =\n {}]",
+                headers.join(", "),
+                val.into_iter()
                     .map(|x| {
                         x.into_iter()
                             .map(|x| x.into_string())
@@ -378,7 +382,8 @@ impl Value {
                             .join(", ")
                     })
                     .collect::<Vec<_>>()
-                .join("\n"),
+                    .join("\n")
+            ),
             Value::RowStream {
                 headers, stream, ..
             } => stream.into_string(headers),
@@ -393,6 +398,138 @@ impl Value {
             span: Span::unknown(),
         }
     }
+
+    pub fn follow_column_path(self, column_path: &[PathMember]) -> Result<Value, ShellError> {
+        let mut current = self;
+        for member in column_path {
+            // FIXME: this uses a few extra clones for simplicity, but there may be a way
+            // to traverse the path without them
+            match member {
+                PathMember::Int {
+                    val: count,
+                    span: origin_span,
+                } => {
+                    // Treat a numeric path member as `nth <val>`
+                    match &mut current {
+                        Value::List { val, .. } => {
+                            if let Some(item) = val.get(*count) {
+                                current = item.clone();
+                            } else {
+                                return Err(ShellError::AccessBeyondEnd(val.len(), *origin_span));
+                            }
+                        }
+                        Value::ValueStream { stream, .. } => {
+                            if let Some(item) = stream.nth(*count) {
+                                current = item;
+                            } else {
+                                return Err(ShellError::AccessBeyondEndOfStream(*origin_span));
+                            }
+                        }
+                        Value::Table { headers, val, span } => {
+                            if let Some(row) = val.get(*count) {
+                                current = Value::Table {
+                                    headers: headers.clone(),
+                                    val: vec![row.clone()],
+                                    span: *span,
+                                }
+                            } else {
+                                return Err(ShellError::AccessBeyondEnd(val.len(), *origin_span));
+                            }
+                        }
+                        Value::RowStream {
+                            headers,
+                            stream,
+                            span,
+                        } => {
+                            if let Some(row) = stream.nth(*count) {
+                                current = Value::Table {
+                                    headers: headers.clone(),
+                                    val: vec![row.clone()],
+                                    span: *span,
+                                }
+                            } else {
+                                return Err(ShellError::AccessBeyondEndOfStream(*origin_span));
+                            }
+                        }
+                        x => {
+                            return Err(ShellError::IncompatiblePathAccess(
+                                format!("{}", x.get_type()),
+                                *origin_span,
+                            ))
+                        }
+                    }
+                }
+                PathMember::String {
+                    val,
+                    span: origin_span,
+                } => match &mut current {
+                    Value::Table {
+                        headers,
+                        val: cells,
+                        span,
+                    } => {
+                        let mut found = false;
+                        for header in headers.iter().enumerate() {
+                            if header.1 == val {
+                                found = true;
+
+                                let mut column = vec![];
+                                for row in cells {
+                                    column.push(row[header.0].clone())
+                                }
+
+                                current = Value::List {
+                                    val: column,
+                                    span: *span,
+                                };
+                                break;
+                            }
+                        }
+
+                        if !found {
+                            return Err(ShellError::CantFindColumn(*origin_span));
+                        }
+                    }
+                    Value::RowStream {
+                        headers,
+                        stream,
+                        span,
+                    } => {
+                        let mut found = false;
+                        for header in headers.iter().enumerate() {
+                            if header.1 == val {
+                                found = true;
+
+                                let mut column = vec![];
+                                for row in stream {
+                                    column.push(row[header.0].clone())
+                                }
+
+                                current = Value::List {
+                                    val: column,
+                                    span: *span,
+                                };
+                                break;
+                            }
+                        }
+
+                        if !found {
+                            //FIXME: add "did you mean"
+                            return Err(ShellError::CantFindColumn(*origin_span));
+                        }
+                    }
+                    x => {
+                        return Err(ShellError::IncompatiblePathAccess(
+                            format!("{}", x.get_type()),
+                            *origin_span,
+                        ))
+                    }
+                },
+            }
+        }
+
+        Ok(current)
+    }
 }
 
 impl PartialEq for Value {

src/tests.rs

@@ -254,3 +254,23 @@ fn build_string3() -> TestResult {
         "nushell rocks",
     )
 }
+
+#[test]
+fn cell_path_subexpr1() -> TestResult {
+    run_test("([[lang, gems]; [nu, 100]]).lang", "[nu]")
+}
+
+#[test]
+fn cell_path_subexpr2() -> TestResult {
+    run_test("([[lang, gems]; [nu, 100]]).lang.0", "nu")
+}
+
+#[test]
+fn cell_path_var1() -> TestResult {
+    run_test("let x = [[lang, gems]; [nu, 100]]; $x.lang", "[nu]")
+}
+
+#[test]
+fn cell_path_var2() -> TestResult {
+    run_test("let x = [[lang, gems]; [nu, 100]]; $x.lang.0", "nu")
+}