Merge pull request #69 from kubouch/simple-module

Primitive module implementation

crates/nu-command/src/default_context.rs

@@ -7,7 +7,7 @@ use nu_protocol::{
 
 use crate::{
     where_::Where, Alias, Benchmark, BuildString, Def, Do, Each, External, For, Git, GitCheckout,
-    If, Length, Let, LetEnv, Lines, ListGitBranches, Ls, Table,
+    If, Length, Let, LetEnv, Lines, ListGitBranches, Ls, Module, Table, Use,
 };
 
 pub fn create_default_context() -> Rc<RefCell<EngineState>> {
@@ -46,6 +46,10 @@ pub fn create_default_context() -> Rc<RefCell<EngineState>> {
 
         working_set.add_decl(Box::new(Ls));
 
+        working_set.add_decl(Box::new(Module));
+
+        working_set.add_decl(Box::new(Use));
+
         working_set.add_decl(Box::new(Table));
 
         working_set.add_decl(Box::new(External));

crates/nu-command/src/lib.rs

@@ -15,8 +15,10 @@ mod let_env;
 mod lines;
 mod list_git_branches;
 mod ls;
+mod module;
 mod run_external;
 mod table;
+mod use_;
 mod where_;
 
 pub use alias::Alias;
@@ -36,5 +38,7 @@ pub use let_env::LetEnv;
 pub use lines::Lines;
 pub use list_git_branches::ListGitBranches;
 pub use ls::Ls;
+pub use module::Module;
 pub use run_external::External;
 pub use table::Table;
+pub use use_::Use;

crates/nu-command/src/module.rs

@@ -0,0 +1,34 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EvaluationContext};
+use nu_protocol::{Signature, SyntaxShape, Value};
+
+pub struct Module;
+
+impl Command for Module {
+    fn name(&self) -> &str {
+        "module"
+    }
+
+    fn usage(&self) -> &str {
+        "Define a custom module"
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("module")
+            .required("module_name", SyntaxShape::String, "module name")
+            .required(
+                "block",
+                SyntaxShape::Block(Some(vec![])),
+                "body of the module",
+            )
+    }
+
+    fn run(
+        &self,
+        _context: &EvaluationContext,
+        call: &Call,
+        _input: Value,
+    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
+        Ok(Value::Nothing { span: call.head })
+    }
+}

crates/nu-command/src/use_.rs

@@ -0,0 +1,28 @@
+use nu_protocol::ast::Call;
+use nu_protocol::engine::{Command, EvaluationContext};
+use nu_protocol::{Signature, SyntaxShape, Value};
+
+pub struct Use;
+
+impl Command for Use {
+    fn name(&self) -> &str {
+        "use"
+    }
+
+    fn usage(&self) -> &str {
+        "Use definitions from a module"
+    }
+
+    fn signature(&self) -> nu_protocol::Signature {
+        Signature::build("use").required("module_name", SyntaxShape::String, "module name")
+    }
+
+    fn run(
+        &self,
+        _context: &EvaluationContext,
+        call: &Call,
+        _input: Value,
+    ) -> Result<nu_protocol::Value, nu_protocol::ShellError> {
+        Ok(Value::Nothing { span: call.head })
+    }
+}

crates/nu-parser/src/errors.rs

@@ -65,6 +65,10 @@ pub enum ParseError {
     #[diagnostic(code(nu::parser::variable_not_found), url(docsrs))]
     VariableNotFound(#[label = "variable not found"] Span),
 
+    #[error("Module not found.")]
+    #[diagnostic(code(nu::parser::module_not_found), url(docsrs))]
+    ModuleNotFound(#[label = "module not found"] Span),
+
     #[error("Unknown command.")]
     #[diagnostic(
         code(nu::parser::unknown_command),

crates/nu-parser/src/parser.rs

@@ -10,7 +10,7 @@ use nu_protocol::{
         RangeInclusion, RangeOperator, Statement,
     },
     engine::StateWorkingSet,
-    span, Flag, PositionalArg, Signature, Span, SyntaxShape, Type, VarId,
+    span, DeclId, Flag, PositionalArg, Signature, Span, SyntaxShape, Type, VarId,
 };
 
 #[derive(Debug, Clone)]
@@ -2649,6 +2649,236 @@ pub fn parse_alias(
     )
 }
 
+pub fn parse_module(
+    working_set: &mut StateWorkingSet,
+    spans: &[Span],
+) -> (Statement, Option<ParseError>) {
+    // TODO: Currently, module is closing over its parent scope (i.e., defs in the parent scope are
+    // visible and usable in this module's scope). We might want to disable that. How?
+
+    let mut error = None;
+    let bytes = working_set.get_span_contents(spans[0]);
+
+    // parse_def() equivalent
+    if bytes == b"module" && spans.len() >= 3 {
+        let (module_name_expr, err) = parse_string(working_set, spans[1]);
+        error = error.or(err);
+
+        let module_name = module_name_expr
+            .as_string()
+            .expect("internal error: module name is not a string");
+
+        // parse_block_expression() equivalent
+        let block_span = spans[2];
+        let block_bytes = working_set.get_span_contents(block_span);
+        let mut start = block_span.start;
+        let mut end = block_span.end;
+
+        if block_bytes.starts_with(b"{") {
+            start += 1;
+        } else {
+            return (
+                garbage_statement(spans),
+                Some(ParseError::Expected("block".into(), block_span)),
+            );
+        }
+
+        if block_bytes.ends_with(b"}") {
+            end -= 1;
+        } else {
+            error = error.or_else(|| {
+                Some(ParseError::Unclosed(
+                    "}".into(),
+                    Span {
+                        start: end,
+                        end: end + 1,
+                    },
+                ))
+            });
+        }
+
+        let block_span = Span { start, end };
+
+        let source = working_set.get_span_contents(block_span);
+
+        let (output, err) = lex(source, start, &[], &[]);
+        error = error.or(err);
+
+        working_set.enter_scope();
+
+        // Do we need block parameters?
+
+        let (output, err) = lite_parse(&output);
+        error = error.or(err);
+
+        // We probably don't need $it
+
+        // we're doing parse_block() equivalent
+        // let (mut output, err) = parse_block(working_set, &output, false);
+
+        for pipeline in &output.block {
+            if pipeline.commands.len() == 1 {
+                parse_def_predecl(working_set, &pipeline.commands[0].parts);
+            }
+        }
+
+        let mut exports: Vec<(Vec<u8>, DeclId)> = vec![];
+
+        let block: Block = output
+            .block
+            .iter()
+            .map(|pipeline| {
+                if pipeline.commands.len() == 1 {
+                    // this one here is doing parse_statement() equivalent
+                    // let (stmt, err) = parse_statement(working_set, &pipeline.commands[0].parts);
+                    let name = working_set.get_span_contents(pipeline.commands[0].parts[0]);
+
+                    let (stmt, err) = match name {
+                        // TODO: Here we can add other stuff that's alowed for modules
+                        b"def" => {
+                            let (stmt, err) = parse_def(working_set, &pipeline.commands[0].parts);
+
+                            if err.is_none() {
+                                let decl_name =
+                                    working_set.get_span_contents(pipeline.commands[0].parts[1]);
+
+                                let decl_id = working_set
+                                    .find_decl(decl_name)
+                                    .expect("internal error: failed to find added declaration");
+
+                                // TODO: Later, we want to put this behind 'export'
+                                exports.push((decl_name.into(), decl_id));
+                            }
+
+                            (stmt, err)
+                        }
+                        _ => (
+                            garbage_statement(&pipeline.commands[0].parts),
+                            Some(ParseError::Expected("def".into(), block_span)),
+                        ),
+                    };
+
+                    if error.is_none() {
+                        error = err;
+                    }
+
+                    stmt
+                } else {
+                    error = Some(ParseError::Expected("not a pipeline".into(), block_span));
+                    garbage_statement(spans)
+                }
+            })
+            .into();
+
+        let block = block.with_exports(exports);
+
+        working_set.exit_scope();
+
+        let block_id = working_set.add_module(&module_name, block);
+
+        let block_expr = Expression {
+            expr: Expr::Block(block_id),
+            span: block_span,
+            ty: Type::Block,
+            custom_completion: None,
+        };
+
+        let module_decl_id = working_set
+            .find_decl(b"module")
+            .expect("internal error: missing module command");
+
+        let call = Box::new(Call {
+            head: spans[0],
+            decl_id: module_decl_id,
+            positional: vec![module_name_expr, block_expr],
+            named: vec![],
+        });
+
+        (
+            Statement::Pipeline(Pipeline::from_vec(vec![Expression {
+                expr: Expr::Call(call),
+                span: span(spans),
+                ty: Type::Unknown,
+                custom_completion: None,
+            }])),
+            error,
+        )
+    } else {
+        (
+            garbage_statement(spans),
+            Some(ParseError::UnknownState(
+                "Expected structure: module <name> {}".into(),
+                span(spans),
+            )),
+        )
+    }
+}
+
+pub fn parse_use(
+    working_set: &mut StateWorkingSet,
+    spans: &[Span],
+) -> (Statement, Option<ParseError>) {
+    let mut error = None;
+    let bytes = working_set.get_span_contents(spans[0]);
+
+    // TODO: Currently, this directly imports the module's definitions into the current scope.
+    // Later, we want to put them behind the module's name and add selective importing
+    if bytes == b"use" && spans.len() >= 2 {
+        let (module_name_expr, err) = parse_string(working_set, spans[1]);
+        error = error.or(err);
+
+        let module_name = module_name_expr
+            .as_string()
+            .expect("internal error: module name is not a string");
+
+        let module_name_bytes = module_name.as_bytes().to_vec();
+
+        let exports = if let Some(block_id) = working_set.find_module(&module_name_bytes) {
+            // TODO: Since we don't use the Block at all, we might just as well create a separate
+            // Module that holds only the exports, without having Blocks in the way.
+            working_set.get_block(block_id).exports.clone()
+        } else {
+            return (
+                garbage_statement(spans),
+                Some(ParseError::ModuleNotFound(spans[1])),
+            );
+        };
+
+        // Extend the current scope with the module's exports
+        working_set.activate_overlay(exports);
+
+        // Create the Use command call
+        let use_decl_id = working_set
+            .find_decl(b"use")
+            .expect("internal error: missing use command");
+
+        let call = Box::new(Call {
+            head: spans[0],
+            decl_id: use_decl_id,
+            positional: vec![module_name_expr],
+            named: vec![],
+        });
+
+        (
+            Statement::Pipeline(Pipeline::from_vec(vec![Expression {
+                expr: Expr::Call(call),
+                span: span(spans),
+                ty: Type::Unknown,
+                custom_completion: None,
+            }])),
+            error,
+        )
+    } else {
+        (
+            garbage_statement(spans),
+            Some(ParseError::UnknownState(
+                "Expected structure: use <name>".into(),
+                span(spans),
+            )),
+        )
+    }
+}
+
 pub fn parse_let(
     working_set: &mut StateWorkingSet,
     spans: &[Span],
@@ -2707,6 +2937,8 @@ pub fn parse_statement(
         b"def" => parse_def(working_set, spans),
         b"let" => parse_let(working_set, spans),
         b"alias" => parse_alias(working_set, spans),
+        b"module" => parse_module(working_set, spans),
+        b"use" => parse_use(working_set, spans),
         _ => {
             let (expr, err) = parse_expression(working_set, spans);
             (Statement::Pipeline(Pipeline::from_vec(vec![expr])), err)

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

@@ -1,6 +1,6 @@
 use std::ops::{Index, IndexMut};
 
-use crate::Signature;
+use crate::{DeclId, Signature};
 
 use super::Statement;
 
@@ -8,6 +8,7 @@ use super::Statement;
 pub struct Block {
     pub signature: Box<Signature>,
     pub stmts: Vec<Statement>,
+    pub exports: Vec<(Vec<u8>, DeclId)>, // Assuming just defs for now
 }
 
 impl Block {
@@ -45,6 +46,15 @@ impl Block {
         Self {
             signature: Box::new(Signature::new("")),
             stmts: vec![],
+            exports: vec![],
+        }
+    }
+
+    pub fn with_exports(self, exports: Vec<(Vec<u8>, DeclId)>) -> Self {
+        Self {
+            signature: self.signature,
+            stmts: self.stmts,
+            exports,
         }
     }
 }
@@ -57,6 +67,7 @@ where
         Self {
             signature: Box::new(Signature::new("")),
             stmts: stmts.collect(),
+            exports: vec![],
         }
     }
 }

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

@@ -17,6 +17,7 @@ pub struct ScopeFrame {
     vars: HashMap<Vec<u8>, VarId>,
     decls: HashMap<Vec<u8>, DeclId>,
     aliases: HashMap<Vec<u8>, Vec<Span>>,
+    modules: HashMap<Vec<u8>, BlockId>,
 }
 
 impl ScopeFrame {
@@ -25,6 +26,7 @@ impl ScopeFrame {
             vars: HashMap::new(),
             decls: HashMap::new(),
             aliases: HashMap::new(),
+            modules: HashMap::new(),
         }
     }
 
@@ -76,6 +78,9 @@ impl EngineState {
             for item in first.aliases.into_iter() {
                 last.aliases.insert(item.0, item.1);
             }
+            for item in first.modules.into_iter() {
+                last.modules.insert(item.0, item.1);
+            }
         }
     }
 
@@ -295,6 +300,37 @@ impl<'a> StateWorkingSet<'a> {
         self.num_blocks() - 1
     }
 
+    pub fn add_module(&mut self, name: &str, block: Block) -> BlockId {
+        let name = name.as_bytes().to_vec();
+
+        self.delta.blocks.push(block);
+        let block_id = self.num_blocks() - 1;
+
+        let scope_frame = self
+            .delta
+            .scope
+            .last_mut()
+            .expect("internal error: missing required scope frame");
+
+        scope_frame.modules.insert(name, block_id);
+
+        block_id
+    }
+
+    pub fn activate_overlay(&mut self, overlay: Vec<(Vec<u8>, DeclId)>) {
+        // TODO: This will overwrite all existing definitions in a scope. When we add deactivate,
+        // we need to re-think how make it recoverable.
+        let scope_frame = self
+            .delta
+            .scope
+            .last_mut()
+            .expect("internal error: missing required scope frame");
+
+        for (name, decl_id) in overlay {
+            scope_frame.decls.insert(name, decl_id);
+        }
+    }
+
     pub fn next_span_start(&self) -> usize {
         self.permanent_state.next_span_start() + self.delta.file_contents.len()
     }
@@ -380,6 +416,22 @@ impl<'a> StateWorkingSet<'a> {
         None
     }
 
+    pub fn find_module(&self, name: &[u8]) -> Option<BlockId> {
+        for scope in self.delta.scope.iter().rev() {
+            if let Some(block_id) = scope.modules.get(name) {
+                return Some(*block_id);
+            }
+        }
+
+        for scope in self.permanent_state.scope.iter().rev() {
+            if let Some(block_id) = scope.modules.get(name) {
+                return Some(*block_id);
+            }
+        }
+
+        None
+    }
+
     // pub fn update_decl(&mut self, decl_id: usize, block: Option<BlockId>) {
     //     let decl = self.get_decl_mut(decl_id);
     //     decl.body = block;