expression type check, but list comprehension done in a bad way for now...

nac3core/src/typecheck/context/inference_context.rs

@@ -6,12 +6,12 @@ use rustpython_parser::ast;
 use std::boxed::Box;
 use std::collections::HashMap;
 
-struct ContextStack<'a> {
+pub struct ContextStack {
     /// stack level, starts from 0
-    level: u32,
+    pub level: u32,
     /// stack of symbol definitions containing (name, level) where `level` is the smallest level
     /// where the name is assigned a value
-    sym_def: Vec<(&'a str, u32)>,
+    pub sym_def: Vec<(String, u32)>,
 }
 
 pub struct InferenceContext<'a> {
@@ -25,9 +25,9 @@ pub struct InferenceContext<'a> {
     /// identifier to (type, readable, location) mapping.
     /// an identifier might be defined earlier but has no value (for some code path), thus not
     /// readable.
-    sym_table: HashMap<&'a str, (Type, bool, Location)>,
+    pub sym_table: HashMap<String, (Type, bool, Location)>,
     /// stack
-    stack: ContextStack<'a>,
+    pub stack: ContextStack,
 }
 
 // non-trivial implementations here
@@ -52,7 +52,7 @@ impl<'a> InferenceContext<'a> {
     /// execute the function with new scope.
     /// variable assignment would be limited within the scope (not readable outside), and type
     /// returns the list of variables assigned within the scope, and the result of the function
-    pub fn with_scope<F, R>(&mut self, f: F) -> (Vec<(&'a str, Type, Location)>, R)
+    pub fn with_scope<F, R>(&mut self, f: F) -> (Vec<(String, Type, Location)>, R)
     where
         F: FnOnce(&mut Self) -> R,
     {
@@ -64,7 +64,7 @@ impl<'a> InferenceContext<'a> {
             let (_, level) = self.stack.sym_def.last().unwrap();
             if *level > self.stack.level {
                 let (name, _) = self.stack.sym_def.pop().unwrap();
-                let (t, b, l) = self.sym_table.get_mut(name).unwrap();
+                let (t, b, l) = self.sym_table.get_mut(&name).unwrap();
                 // set it to be unreadable
                 *b = false;
                 poped_names.push((name, t.clone(), *l));
@@ -77,8 +77,8 @@ impl<'a> InferenceContext<'a> {
 
     /// assign a type to an identifier.
     /// may return error if the identifier was defined but with different type
-    pub fn assign(&mut self, name: &'a str, ty: Type, loc: ast::Location) -> Result<Type, String> {
+    pub fn assign(&mut self, name: String, ty: Type, loc: ast::Location) -> Result<Type, String> {
-        if let Some((t, x, _)) = self.sym_table.get_mut(name) {
+        if let Some((t, x, _)) = self.sym_table.get_mut(&name) {
             if t == &ty {
                 if !*x {
                     self.stack.sym_def.push((name, self.stack.level));
@@ -89,7 +89,7 @@ impl<'a> InferenceContext<'a> {
                 Err("different types".into())
             }
         } else {
-            self.stack.sym_def.push((name, self.stack.level));
+            self.stack.sym_def.push((name.clone(), self.stack.level));
             self.sym_table.insert(
                 name,
                 (ty.clone(), true, Location::CodeRange(self.file, loc)),
@@ -124,6 +124,11 @@ impl<'a> InferenceContext<'a> {
             self.resolver.get_symbol_location(name)
         }
     }
+
+    /// check if an identifier is already defined
+    pub fn defined(&self, name: &String) -> bool {
+        self.sym_table.get(name).is_some()
+    }
 }
 
 // trivial getters:

nac3core/src/typecheck/expression_inference.rs

@@ -1,4 +1,5 @@
 use std::convert::TryInto;
+use std::fs::create_dir_all;
 
 use crate::typecheck::context::InferenceContext;
 use crate::typecheck::inference_core;
@@ -6,11 +7,12 @@ use crate::typecheck::magic_methods;
 use crate::typecheck::typedef::{Type, TypeEnum};
 use crate::typecheck::primitives;
 use rustpython_parser::ast;
+use rustpython_parser::ast::fold::Fold;
 
 use super::inference_core::resolve_call;
 
 pub struct ExpressionTypeInferencer<'a> {
-    pub ctx: InferenceContext<'a>  //FIXME: may need to remove this pub
+    pub ctx: InferenceContext<'a>
 }
 
 impl<'a> ExpressionTypeInferencer<'a> { // NOTE: add location here in the function parameter for better error message?
@@ -211,7 +213,16 @@ impl<'a> ExpressionTypeInferencer<'a> { // NOTE: add location here in the functi
         }
     }
 
-    fn infer_slice(&self, lower: &Option<Box<ast::Expr<Option<Type>>>>, upper: &Option<Box<ast::Expr<Option<Type>>>>, step: &Option<Box<ast::Expr<Option<Type>>>>) -> Result<Option<Type>, String> {
+    fn infer_subscript(&self, value: &Box<ast::Expr<Option<Type>>>, slice: &Box<ast::Expr<Option<Type>>>) -> Result<Option<Type>, String> {
+        // let tt = value.custom.ok_or_else(|| "no value".to_string())?.as_ref();
+
+        let t = if let TypeEnum::ParametricType(primitives::LIST_TYPE, ls) = value.custom.as_ref().ok_or_else(|| "no value".to_string())?.as_ref() {
+            ls[0].clone()
+        } else {
+            return Err("subscript is not supported for types other than list".into());
+        };
+
+        if let ast::ExprKind::Slice {lower, upper, step} = &slice.node {
             let int32_type = self.ctx.get_primitive(primitives::INT32_TYPE);
             let l = lower.as_ref().map_or(
                 Ok(&int32_type),
@@ -224,23 +235,10 @@ impl<'a> ExpressionTypeInferencer<'a> { // NOTE: add location here in the functi
                 |x| x.custom.as_ref().ok_or("step cannot be typped".to_string()))?;
             
             if l == &int32_type && u == &int32_type && s == &int32_type {
-            Ok(Some(self.ctx.get_primitive(primitives::SLICE_TYPE)))
+                Ok(value.custom.clone())
             } else {
                 Err("slice must be int32 type".into())
             }
-    }
-
-    fn infer_subscript(&self, value: &Box<ast::Expr<Option<Type>>>, slice: &Box<ast::Expr<Option<Type>>>) -> Result<Option<Type>, String> {
-        // let tt = value.custom.ok_or_else(|| "no value".to_string())?.as_ref();
-
-        let t = if let TypeEnum::ParametricType(primitives::LIST_TYPE, ls) = value.custom.as_ref().ok_or_else(|| "no value".to_string())?.as_ref() {
-            ls[0].clone()
-        } else {
-            return Err("subscript is not supported for types other than list".into());
-        };
-
-       if slice.custom == Some(self.ctx.get_primitive(primitives::SLICE_TYPE)) {
-           Ok(value.custom.clone())
         } else if slice.custom == Some(self.ctx.get_primitive(primitives::INT32_TYPE)) {
             Ok(Some(t))
         } else {
@@ -260,21 +258,56 @@ impl<'a> ExpressionTypeInferencer<'a> { // NOTE: add location here in the functi
         }
     }
 
-    fn infer_simple_binding(&mut self, name: &'a ast::Expr<Option<Type>>, ty: Type) -> Result<(), String> {
+    fn infer_list_comprehesion(&mut self, elt: &Box<ast::Expr<Option<Type>>>, generators: &Vec<ast::Comprehension<Option<Type>>>) -> Result<Option<Type>, String> {
+        if generators[0]
+            .ifs
+            .iter()
+            .all(|x| x.custom == Some(self.ctx.get_primitive(primitives::BOOL_TYPE))) {
+                Ok(Some(TypeEnum::ParametricType(
+                    primitives::LIST_TYPE, 
+                    vec![elt.custom.clone().ok_or_else(|| "elements should have value".to_string())?]).into()))
+            } else {
+                Err("test must be bool".into())
+            }       
+    }
+
+    fn fold_comprehension_first(&mut self, node: ast::Comprehension<Option<Type>>) -> Result<ast::Comprehension<Option<Type>>, String> {
+        Ok(ast::Comprehension {
+            target: node.target,
+            iter: Box::new(self.fold_expr(*node.iter)?),
+            ifs: node.ifs,
+            is_async: node.is_async
+        })
+    }
+
+    fn fold_comprehension_second(&mut self, node: ast::Comprehension<Option<Type>>) -> Result<ast::Comprehension<Option<Type>>, String> {
+        Ok(ast::Comprehension {
+            target: Box::new(self.fold_expr(*node.target)?),
+            iter: node.iter,
+            ifs: node
+                .ifs
+                .into_iter()
+                .map(|x| self.fold_expr(x))
+                .collect::<Result<Vec<_>, _>>()?,
+            is_async: node.is_async
+        })
+    }
+
+    fn infer_simple_binding(&mut self, name: &ast::Expr<Option<Type>>, ty: Type) -> Result<(), String> {
         match &name.node {
             ast::ExprKind::Name {id, ctx: _} => {
                 if id == "_" {
                     Ok(())
-                } else if self.ctx.defined(id.as_str()) {
+                } else if self.ctx.defined(id) {
                     Err("duplicated naming".into())
                 } else {
-                    self.ctx.assign(id.as_str(), ty, name.location)?;
+                    self.ctx.assign(id.clone(), ty, name.location)?;
                     Ok(())
                 }
             }
     
             ast::ExprKind::Tuple {elts, ctx: _} => {
-                if let TypeEnum::ParametricType(TUPLE_TYPE, ls) = ty.as_ref() {
+                if let TypeEnum::ParametricType(primitives::TUPLE_TYPE, ls) = ty.as_ref() {
                     if elts.len() == ls.len() {
                         for (a, b) in elts.iter().zip(ls.iter()) {
                             self.infer_simple_binding(a, b.clone())?;
@@ -287,37 +320,12 @@ impl<'a> ExpressionTypeInferencer<'a> { // NOTE: add location here in the functi
                     Err("not supported".into())
                 }
             }
-
             _ => Err("not supported".into())
         }
     }
-
-    fn infer_list_comprehesion(&mut self, elt: &Box<ast::Expr<Option<Type>>>, generators: &Vec<ast::Comprehension<Option<Type>>>) -> Result<Option<Type>, String> {
-        if generators.len() != 1 {
-            Err("only 1 generator statement is supported".into())
-        } else {
-            let gen = &generators[0];
-            if gen.is_async {
-                Err("async is not supported".into())
-            } else {
-                let iter_type = gen.iter.custom.as_ref().ok_or("no value".to_string())?.as_ref();
-                if let TypeEnum::ParametricType(primitives::LIST_TYPE, ref ls) = iter_type {
-                    self.ctx.with_scope(|x| {
-                        // x.infer_simple_binding(&gen.target, ls[0].clone()); // FIXME:
-                        Ok(None)
-                    }).1
-                } else {
-                    Err("iteration is supported for list only".into())
-                }
-            }
-        }
 }
 
 
-
-}
-
-// REVIEW: field custom: from () to Option<Type> or just Option<Type>?
 impl<'a> ast::fold::Fold<Option<Type>> for ExpressionTypeInferencer<'a> {
     type TargetU = Option<Type>;
     type Error = String;
@@ -326,28 +334,54 @@ impl<'a> ast::fold::Fold<Option<Type>> for ExpressionTypeInferencer<'a> {
         Ok(user)
     }
     
-    // override the default fold_comprehension to avoid errors caused by folding locally bound variable
-    fn fold_comprehension(&mut self, node: ast::Comprehension<Option<Type>>) -> Result<ast::Comprehension<Self::TargetU>, Self::Error> {
-        Ok(ast::Comprehension {
-            target: node.target,
-            iter: Box::new(self.fold_expr(*node.iter)?),
-            ifs: node.ifs,
-            is_async: node.is_async
-        })
-    }
-
     fn fold_expr(&mut self, node: ast::Expr<Option<Type>>) -> Result<ast::Expr<Self::TargetU>, Self::Error> {
         assert_eq!(node.custom, None); // NOTE: should pass
         let mut expr = node;
-        if let ast::Expr {location: _, custom: _, node: ast::ExprKind::ListComp {elt, generators } } = expr { 
+        
+        if let ast::Expr {location, custom, node: ast::ExprKind::ListComp {elt, generators } } = expr { 
+            // is list comprehension, only fold generators which does not include unknown identifiers introduced by list comprehension
+            if generators.len() != 1 {
+                return Err("only 1 generator statement is supported".into())
+            }
+            let generators_first_folded = generators
+                .into_iter()
+                .map(|x| self.fold_comprehension_first(x)).collect::<Result<Vec<_>, _>>()?;
+
+            let gen = &generators_first_folded[0];
+            let iter_type = gen.iter.custom.as_ref().ok_or("no value".to_string())?.as_ref();
+
+            if let TypeEnum::ParametricType(primitives::LIST_TYPE, ls) = iter_type {
+                self.ctx.stack.level += 1; // FIXME: how to use with_scope??
+
+                self.infer_simple_binding(&gen.target, ls[0].clone())?;
                 expr = ast::Expr {
-                location: expr.location,
+                    location,
-                custom: expr.custom,
+                    custom,
                     node: ast::ExprKind::ListComp {
-                    elt,
+                        elt: Box::new(self.fold_expr(*elt)?),
-                    generators: generators.into_iter().map(|x| self.fold_comprehension(x)).collect::<Result<Vec<_>, _>>()?
+                        generators: generators_first_folded
+                            .into_iter()
+                            .map(|x| self.fold_comprehension_second(x))
+                            .collect::<Result<Vec<_>, _>>()?
                     }
                 };
+
+                self.ctx.stack.level -= 1;
+                while !self.ctx.stack.sym_def.is_empty() {
+                    let (_, level) = self.ctx.stack.sym_def.last().unwrap();
+                    if *level > self.ctx.stack.level {
+                        let (name, _) = self.ctx.stack.sym_def.pop().unwrap();
+                        let (t, b, l) = self.ctx.sym_table.get_mut(&name).unwrap();
+                        // set it to be unreadable
+                        *b = false;
+                    } else {
+                        break;
+                    }
+                }
+
+            } else {
+                return Err("iteration is supported for list only".into());
+            }
         } else {
             // if not listcomp which requires special handling, skip current level, make sure child nodes have their type
             expr = ast::fold::fold_expr(self, expr)?;
@@ -429,15 +463,15 @@ impl<'a> ast::fold::Fold<Option<Type>> for ExpressionTypeInferencer<'a> {
                     node: expr.node
                 }),
 
-            // REVIEW: add a new primitive type for slice and do type check of bounds here?
+            /* // REVIEW: add a new primitive type for slice and do type check of bounds here?
             ast::ExprKind::Slice {lower, upper, step } => 
                 Ok(ast::Expr {
                     location: expr.location,
                     custom: self.infer_slice(lower, upper, step)?, 
                     node: expr.node
-                }),
+                }), */
 
-            ast::ExprKind::Subscript {value, slice, ctx} => 
+            ast::ExprKind::Subscript {value, slice, ctx: _} => 
                 Ok(ast::Expr {
                     location: expr.location,
                     custom: self.infer_subscript(value, slice)?,
@@ -451,15 +485,14 @@ impl<'a> ast::fold::Fold<Option<Type>> for ExpressionTypeInferencer<'a> {
                     node: expr.node
                 }),
 
-            ast::ExprKind::ListComp {elt, generators} => 
+            ast::ExprKind::ListComp {elt, generators} => {
+
                 Ok(ast::Expr {
                     location: expr.location,
                     custom: self.infer_list_comprehesion(elt, generators)?,
                     node: expr.node
-                }),
+                })
-
+            }
-            
-
 
             _ => { // not supported
                 Err("not supported yet".into())