Merge pull request #21 from mist-go/improved-statements

Improved statements

parser/src/ast.rs

@@ -1,9 +1,7 @@
-use std::collections::HashMap;
-
 use serde::Serialize;
 
 #[derive(Debug, Clone, Serialize)]
-pub struct FieldList(pub HashMap<String, (bool, TypeExpr)>);
+pub struct FieldList(pub Vec<(String, bool, TypeExpr)>);
 
 #[derive(Debug, Clone, Serialize)]
 pub struct ParamList(pub Vec<VarDecl>);
@@ -83,7 +81,7 @@ pub enum Postfix {
     FieldAccess(String),
     Call(Vec<Expression>),
     MacroCall(String),
-    StructCall(HashMap<String, Expression>),
+    StructCall(Vec<(String, Expression)>),
     Index(Expression),
     Binary(BinaryOp, Expression),
 }
@@ -102,9 +100,23 @@ pub enum Statement {
 
     VarDecl(VarDeclStmt),
     VarAssign(VarAssignStmt),
-    If(IfStmt),
+    If {
-    While(WhileStmt),
+        initial: StatementBranch,
-    For(ForStmt),
+        else_if: Vec<StatementBranch>,
+        else_branch: Option<Box<Statement>>,
+    },
+    While(StatementBranch),
+    CStyleFor {
+        init: Box<Statement>,
+        condition: Expression,
+        update: Box<Statement>,
+        body: Box<Statement>,
+    },
+    For {
+        pattern: String,
+        iterator: Expression,
+        body: Box<Statement>,
+    },
 
     Return(Option<Expression>),
     Break,
@@ -131,23 +143,8 @@ pub struct VarAssignStmt {
 }
 
 #[derive(Debug, Clone, Serialize)]
-pub struct IfStmt {
+pub struct StatementBranch {
     pub condition: Expression,
-    pub then_branch: Box<Statement>,
-    pub else_branch: Option<Box<Statement>>,
-}
-
-#[derive(Debug, Clone, Serialize)]
-pub struct WhileStmt {
-    pub condition: Expression,
-    pub body: Box<Statement>,
-}
-
-#[derive(Debug, Clone, Serialize)]
-pub struct ForStmt {
-    pub init: (bool, String, Option<Expression>),
-    pub condition: Option<Expression>,
-    pub update: Option<Box<Statement>>,
     pub body: Box<Statement>,
 }
 

parser/src/grammar.pest

@@ -15,7 +15,9 @@ static_path =  { identifier ~ ("::" ~ identifier)* }
 export    =  { "public" }
 mutable   =  { "mut" }
 sharp     = _{ "#" }
-var_decl =  { type_expr ~ mutable? ~ identifier }
+var       =  { "var" }
+var_decl  =  { (var | type_expr) ~ mutable? ~ identifier }
+semicolon = _{ ";" }
 
 // ================= TOP LEVEL =================
 
@@ -66,6 +68,8 @@ statement = _{
   | assign_statement
   | if_stmt
   | while_stmt
+  | c_for_stmt
+  | for_stmt
   | return_stmt
   | break_stmt
   | continue_stmt
@@ -74,26 +78,38 @@ statement = _{
 
 // --- basic statements ---
 
-expr_stmt = { expr ~ ";" }
+expr_stmt = { expr ~ semicolon }
 
-return_stmt = { "return" ~ expr? ~ ";" }
+return_stmt = { "return" ~ expr? ~ semicolon }
 
-break_stmt = { "break" ~ ";" }
+break_stmt = { "break" ~ semicolon }
 
-continue_stmt = { "continue" ~ ";" }
+continue_stmt = { "continue" ~ semicolon }
 
-var_decl_statement = { var_decl ~ ("=" ~ expr)? ~ ";" }
+var_decl_statement = { var_decl ~ ("=" ~ expr)? ~ semicolon }
 
-assign_statement = { expr ~ "=" ~ expr ~ ";" }
+assign_statement = { expr ~ "=" ~ expr ~ semicolon }
+
+else_if = { "else" ~ "if" ~ "(" ~ expr ~ ")" ~ statement }
+
+else_if_list = { else_if* }
 
 if_stmt = {
-    "if" ~ "(" ~ expr ~ ")" ~ statement ~ ("else" ~ statement)?
+    "if" ~ "(" ~ expr ~ ")" ~ statement ~ else_if_list ~ ("else" ~ statement)?
 }
 
 while_stmt = {
     "while" ~ "(" ~ expr ~ ")" ~ statement
 }
 
+c_for_stmt = {
+    "for" ~ "(" ~ statement ~ expr ~ semicolon ~ statement ~ ")" ~ statement
+}
+
+for_stmt = {
+    "for" ~ "(" ~ identifier ~ "in" ~ expr ~ ")" ~ statement
+}
+
 // ================= EXPRESSIONS =================
 tuple_type = { "(" ~ (type_expr ~ ("," ~ type_expr)*)? ~ ")" }
 path_type  = { static_path ~ ("<" ~ (type_expr ~ ("," ~ type_expr)*)? ~ ">")? }
@@ -131,7 +147,7 @@ macro_call_px     = { "!" ~ "(" ~ macro_inner_v* ~ ")" }
 struct_px         = { "{" ~ (struct_field_decl ~ ("," ~ struct_field_decl)*)? ~ ","? ~ "}" }
 index_px          = { "[" ~ expr ~ "]" }
 binary_px         = { bin_op ~ expr }
-bin_op            = { "+" | "-" | "*" | "/" | "%" | "==" | "!=" | "<" | ">" | "<=" | ">=" }
+bin_op            = { "<=" | ">=" | "==" | "!=" | "+" | "-" | "*" | "/" | "%" | "<" | ">" }
 struct_field_decl = { identifier ~ ":" ~ expr }
 
 prefix = {

parser/src/lib.rs

@@ -104,7 +104,7 @@ impl From<pest::iterators::Pair<'_, Rule>> for FieldList {
                 };
                 let param_type = TypeExpr::from(param_inner.next().unwrap());
                 let param_name = param_inner.next().unwrap().as_str().to_string();
-                (param_name, (export, param_type))
+                (param_name, export, param_type)
             })
             .collect();
 
@@ -196,6 +196,20 @@ impl From<pest::iterators::Pair<'_, Rule>> for TopLevel {
     }
 }
 
+impl From<pest::iterators::Pair<'_, Rule>> for StatementBranch {
+    fn from(pair: pest::iterators::Pair<'_, Rule>) -> Self {
+        let mut inner = pair.into_inner();
+
+        let condition = Expression::from(inner.next().unwrap());
+        let body = Statement::from(inner.next().unwrap());
+
+        StatementBranch {
+            condition,
+            body: Box::new(body),
+        }
+    }
+}
+
 impl From<pest::iterators::Pair<'_, Rule>> for TopLevelKind {
     fn from(pair: pest::iterators::Pair<'_, Rule>) -> Self {
         let rule = pair.as_rule();
@@ -303,27 +317,34 @@ impl From<pest::iterators::Pair<'_, Rule>> for Statement {
             Rule::continue_stmt => Statement::Continue,
 
             Rule::if_stmt => {
-                let condition = Expression::from(inner.next().unwrap());
+                let mut inner = inner.skip(2);
-                let then_branch = Statement::from(inner.next().unwrap());
 
-                let else_branch = inner.next().map(Statement::from);
+                Statement::If {
-
+                    initial: pair.into(),
-                Statement::If(IfStmt {
+                    else_if: inner
-                    condition,
+                        .next()
-                    then_branch: Box::new(then_branch),
+                        .unwrap()
-                    else_branch: else_branch.map(Box::new),
+                        .into_inner()
-                })
+                        .map(StatementBranch::from)
+                        .collect(),
+                    else_branch: inner.next().map(Statement::from).map(Box::new),
+                }
             }
 
-            Rule::while_stmt => {
+            Rule::while_stmt => Statement::While(pair.into()),
-                let condition = Expression::from(inner.next().unwrap());
-                let body = Statement::from(inner.next().unwrap());
 
-                Statement::While(WhileStmt {
+            Rule::c_for_stmt => Statement::CStyleFor {
-                    condition,
+                init: Box::new(Statement::from(inner.next().unwrap())),
-                    body: Box::new(body),
+                condition: inner.next().unwrap().into(),
-                })
+                update: Box::new(Statement::from(inner.next().unwrap())),
-            }
+                body: Box::new(Statement::from(inner.next().unwrap())),
+            },
+
+            Rule::for_stmt => Statement::For {
+                pattern: inner.next().unwrap().as_str().to_string(),
+                iterator: inner.next().unwrap().into(),
+                body: Box::new(Statement::from(inner.next().unwrap())),
+            },
 
             Rule::assign_statement => Statement::VarAssign(VarAssignStmt {
                 target: Expression::from(inner.next().unwrap()),
@@ -495,7 +516,13 @@ impl From<pest::iterators::Pair<'_, Rule>> for VarDecl {
             Rule::var_decl => {
                 let mut inner = pair.into_inner();
 
-                let type_ = Some(inner.next().map(TypeExpr::from).unwrap());
+                let type_ = inner.next().and_then(|pair| {
+                    if pair.as_str().trim() == "var" {
+                        None
+                    } else {
+                        Some(TypeExpr::from(pair))
+                    }
+                });
                 let mutable = if inner.peek().unwrap().as_rule() == Rule::mutable {
                     inner.next();
                     true

src/codegen.rs

@@ -1,7 +1,7 @@
 use parser::ast::{
-    Attribute, BinaryOp, Block, Expression, IfStmt, Literal, Path, Postfix, Prefix, Statement,
+    Attribute, BinaryOp, Block, Expression, Literal, Path, Postfix, Prefix, Statement,
-    TopLevel, TopLevelKind, TypeExpr, TypeExprKind, TypePostfix, VarAssignStmt, VarDecl,
+    StatementBranch, TopLevel, TopLevelKind, TypeExpr, TypeExprKind, TypePostfix, VarAssignStmt,
-    VarDeclStmt, WhileStmt,
+    VarDecl, VarDeclStmt,
 };
 
 // ---------------------------------------------------------------------------
@@ -61,6 +61,19 @@ impl RustCodegen {
         }
         self.output.clone()
     }
+
+    pub fn ensure_brackets(&mut self, stmt: &Statement) {
+        match stmt {
+            Statement::Block(_) => stmt.to_rust(self),
+            _ => {
+                self.add_indentedln("{");
+                self.indent += 1;
+                stmt.to_rust(self);
+                self.indent -= 1;
+                self.add_indentedln("}");
+            }
+        }
+    }
 }
 
 impl Default for RustCodegen {
@@ -284,7 +297,7 @@ impl ToRust for TopLevelKind {
                 cg.addln(&format!("{}struct {} {{", vis, name));
                 cg.indent += 1;
 
-                for (field_name, (_, ty)) in &fields.0 {
+                for (field_name, _, ty) in &fields.0 {
                     let ty = ty.get_rust();
                     cg.add_indentedln(&format!("pub {}: {},", field_name, ty));
                 }
@@ -353,36 +366,64 @@ impl ToRust for Statement {
                 cg.add_indentedln(&format!("{} = {};", target.get_rust(), value.get_rust(),));
             }
 
-            Statement::If(IfStmt {
+            Statement::If {
-                condition,
+                initial,
-                then_branch,
+                else_if,
                 else_branch,
-            }) => {
+            } => {
-                cg.add_indentedln(&format!("if {} {{", condition.get_rust()));
+                cg.add_indentedln(&format!("if {}", initial.condition.get_rust()));
-                cg.indent += 1;
+                cg.ensure_brackets(&initial.body);
-                then_branch.to_rust(cg);
+
-                cg.indent -= 1;
+                for else_if_branch in else_if {
-                cg.add_indentedln("}");
+                    cg.add_indentedln(&format!("else if {}", else_if_branch.condition.get_rust()));
+                    cg.ensure_brackets(&else_if_branch.body);
+                }
 
                 if let Some(else_br) = else_branch {
-                    cg.add_indentedln("else {");
+                    cg.add_indentedln("else");
-                    cg.indent += 1;
+                    cg.ensure_brackets(else_br);
-                    else_br.to_rust(cg);
-                    cg.indent -= 1;
-                    cg.add_indentedln("}");
                 }
             }
 
-            Statement::While(WhileStmt { condition, body }) => {
+            Statement::While(StatementBranch { condition, body }) => {
-                cg.add_indentedln(&format!("while {} {{", condition.get_rust()));
+                cg.add_indentedln(&format!("while {}", condition.get_rust()));
+                cg.ensure_brackets(body);
+            }
+
+            Statement::CStyleFor {
+                init,
+                condition,
+                update,
+                body,
+            } => {
+                cg.add_indentedln("{");
                 cg.indent += 1;
-                body.to_rust(cg);
+
+                init.to_rust(cg);
+
+                cg.add_indentedln(&format!("while {}", condition.get_rust()));
+
+                cg.add_indentedln("{");
+                cg.indent += 1;
+
+                cg.ensure_brackets(body);
+
+                update.to_rust(cg);
+
+                cg.indent -= 1;
+                cg.add_indentedln("}");
+
                 cg.indent -= 1;
                 cg.add_indentedln("}");
             }
 
-            Statement::For { .. } => {
+            Statement::For {
-                cg.add_indentedln("// TODO: transform into iterator-based loop");
+                pattern,
+                iterator,
+                body,
+            } => {
+                cg.add_indentedln(&format!("for {} in {}", pattern, iterator.get_rust()));
+                cg.ensure_brackets(body);
             }
 
             Statement::Return(expr) => {

test/src/main.mist

@@ -1,13 +1,7 @@
-#![allow(unused_mut)]
-
-#[derive(Debug)]
-public struct ApiCall {
-    i32 x,
-    i32 y,
-}
-
 void main() {
-    ApiCall call = ApiCall { x: 10, y: 12 };
+    var iter = vec!(1, 2, 3, 4, 5);
 
-    println!("{call:?}");
+    for (i in iter) {
+        println!("{i}");
+    }
 }