parse struct-binding blocks

src/lexer.rs

@@ -219,7 +219,7 @@ where
                 }
 
                 LexerState::TypeTerm(s) => {
-                    if *c == '=' || *c == '.' {
+                    if *c == '=' || *c == '.' || *c == '↦' || *c == ';' {
                         if let Some(token) = state.clone().into_token() {
                             return Some((region, Ok(token)));
                         }

src/parser.rs

@@ -9,12 +9,13 @@ use {
     },
 };
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum ParseError {
     LexError(LexError),
     UnexpectedClose,
     UnexpectedEnd,
     UnexpectedToken,
+    TypeParseError(laddertypes::parser::ParseError)
 }
 
 pub fn parse_expect<It>(
@@ -37,6 +38,8 @@ where
     }
 }
 
+/* parse symbol name
+ */
 pub fn parse_symbol<It>(tokens: &mut Peekable<LTIRLexer<It>>) -> Result<String, ParseError>
 where
     It: Iterator<Item = char>,
@@ -49,10 +52,13 @@ where
     }
 }
 
+/* parse an optional type annotation
+ *  `: T`
+ */
 pub fn parse_type_tag<It>(
     typectx: &Arc<RwLock<laddertypes::dict::TypeDict>>,
     tokens: &mut Peekable<LTIRLexer<It>>,
-) -> Option<TypeTag>
+) -> Result<Option<laddertypes::TypeTerm>, ParseError>
 where
     It: Iterator<Item = char>,
 {
@@ -61,17 +67,110 @@ where
             Ok(LTIRToken::AssignType(typeterm_str)) => {
                 tokens.next();
                 match typectx.write().unwrap().parse(typeterm_str.as_str()) {
-                    Ok(typeterm) => Some(Ok(typeterm)),
-                    Err(parse_error) => Some(Err(TypeError::ParseError(parse_error))),
+                    Ok(typeterm) => Ok(Some(typeterm)),
+                    Err(parse_error) => Err(ParseError::TypeParseError(parse_error)),
                 }
             }
-            _ => None,
+            _ => Ok(None),
         }
     } else {
-        None
+        Ok(None)
     }
 }
 
+#[derive(Debug, PartialEq, Eq)]
+pub enum VariableBinding {
+    Atomic {
+        symbol: String,
+        typtag: Option<laddertypes::TypeTerm>
+    },
+    Struct {
+        members: Vec< VariableBinding >,
+        typtag: Option<laddertypes::TypeTerm>
+    }
+}
+
+impl VariableBinding {
+    pub fn flatten(self) -> Vec<(String, Option<laddertypes::TypeTerm>)> {
+        match self {
+            VariableBinding::Atomic{ symbol, typtag } =>
+                vec![ (symbol, typtag) ],
+            VariableBinding::Struct{ members, typtag } =>
+                members
+                    .into_iter()
+                    .map(|a| a.flatten().into_iter())
+                    .flatten()
+                    .collect()
+        }
+   }
+}
+
+/* parse a symbol binding of the form
+ *     `x`
+ * or  `x : T`
+ */
+pub fn parse_binding_expr<It>(
+    typectx: &Arc<RwLock<laddertypes::dict::TypeDict>>,
+    tokens: &mut Peekable<LTIRLexer<It>>,
+) -> Result< VariableBinding, ParseError>
+where It: Iterator<Item = char>
+{
+    if let Some((region, peektok)) = tokens.peek().clone() {
+        match peektok {
+            Ok(LTIRToken::BlockOpen) => {
+                Ok(VariableBinding::Struct {
+                    members: parse_binding_block(typectx, tokens)?,
+                    typtag: parse_type_tag(typectx, tokens)?
+                })
+            }
+            Ok(LTIRToken::Symbol(_)) => {
+                Ok(VariableBinding::Atomic{
+                    symbol: parse_symbol(tokens)?,
+                    typtag: parse_type_tag(typectx, tokens)?
+                })
+            }
+            Err(err) => Err(ParseError::LexError(err.clone())),
+            _ => Err(ParseError::UnexpectedToken)
+        }
+    } else {
+        Err(ParseError::UnexpectedEnd)
+    }
+}
+
+/* parse a block of symbol bidnings
+ * `{ x:T; y:U; ... }`
+ */
+pub fn parse_binding_block<It>(
+    typectx: &Arc<RwLock<laddertypes::dict::TypeDict>>,
+    tokens: &mut Peekable<LTIRLexer<It>>,
+) -> Result< Vec<VariableBinding>, ParseError>
+where
+    It: Iterator<Item = char>,
+{
+    let _ = parse_expect(tokens, LTIRToken::BlockOpen)?;
+
+    let mut bindings = Vec::new();
+    while let Some((region, peektok)) = tokens.peek() {
+        match peektok {
+            Ok(LTIRToken::BlockClose) => {
+                tokens.next();
+                return Ok(bindings);
+            }
+            Ok(LTIRToken::StatementSep) => {
+                tokens.next();
+            }
+            Ok(_) => {
+                bindings.push(parse_binding_expr(typectx, tokens)?);
+            }
+            Err(err) => {
+                return Err(ParseError::LexError(err.clone()));
+            }
+        }
+    }
+
+    Err(ParseError::UnexpectedEnd)
+}
+
 pub fn parse_statement<It>(
     typectx: &Arc<RwLock<laddertypes::dict::TypeDict>>,
     tokens: &mut Peekable<LTIRLexer<It>>,
@@ -98,13 +197,19 @@ where
                     "let" => {
                         tokens.next();
                         let name = parse_symbol(tokens)?;
-                        let typ = parse_type_tag(typectx, tokens);
+                        let typ = parse_type_tag(typectx, tokens)?;
+                        /* todo
+                        let mut variable_bindings = parse_binding_expr(typectx, tokens)?;
+                        */
                         let _ = parse_expect(tokens, LTIRToken::AssignValue);
                         let val_expr = parse_expr(typectx, tokens)?;
                         let _ = parse_expect(tokens, LTIRToken::StatementSep)?;
 
                         Ok(Statement::LetAssign {
-                            typ,
+                            typ: match typ {
+                                Some(t) => Some(Ok(t)),
+                                None => None
+                            },
                             var_id: name,
                             val_expr,
                         })
@@ -116,7 +221,7 @@ where
                         let _ = parse_expect(tokens, LTIRToken::ExprClose)?;
                         Ok(Statement::WhileLoop {
                             condition: cond,
-                            body: parse_block(typectx, tokens)?,
+                            body: parse_statement_block(typectx, tokens)?,
                         })
                     }
                     "return" => {
@@ -144,7 +249,7 @@ where
     }
 }
 
-pub fn parse_block<It>(
+pub fn parse_statement_block<It>(
     typectx: &Arc<RwLock<laddertypes::dict::TypeDict>>,
     tokens: &mut Peekable<LTIRLexer<It>>,
 ) -> Result<Vec<Statement>, ParseError>
@@ -203,16 +308,12 @@ where
                 if children.len() == 0 {
                     tokens.next();
 
-                    let mut args = Vec::new();
-                    while let Some((region, Ok(LTIRToken::Symbol(_)))) = tokens.peek() {
-                        args.push((parse_symbol(tokens)?, parse_type_tag(typectx, tokens)));
-                    }
-
+                    let mut variable_bindings = parse_binding_expr(typectx, tokens)?;
                     let _ = parse_expect(tokens, LTIRToken::LambdaBody);
                     let body = parse_expr(typectx, tokens)?;
 
                     return Ok(LTExpr::Abstraction {
-                        args,
+                        args: variable_bindings.flatten().into_iter().map(|(s,t)| (s,t.map(|t|Ok(t))) ).collect(),
                         body: Box::new(body),
                     });
                 } else {
@@ -236,7 +337,7 @@ where
                 break;
             }
             Ok(LTIRToken::BlockOpen) => {
-                children.push(LTExpr::block(parse_block(typectx, tokens)?));
+                children.push(LTExpr::block(parse_statement_block(typectx, tokens)?));
             }
             Ok(LTIRToken::BlockClose) => {
                 break;
@@ -250,7 +351,7 @@ where
                     let _ = parse_expect(tokens, LTIRToken::ExprOpen)?;
                     let cond = parse_expr(typectx, tokens)?;
                     let _ = parse_expect(tokens, LTIRToken::ExprClose)?;
-                    let if_expr = LTExpr::block(parse_block(typectx, tokens)?);
+                    let if_expr = LTExpr::block(parse_statement_block(typectx, tokens)?);
                     let mut else_expr = LTExpr::block(vec![]);
 
                     if let Some((region, peektok)) = tokens.peek() {
@@ -292,3 +393,99 @@ where
         Err(ParseError::UnexpectedEnd)
     }
 }
+
+
+
+mod tests {
+    use std::sync::{Arc, RwLock};
+    
+    #[test]
+    fn test_parse_atomic_binding() {
+        let mut lexer = crate::lexer::LTIRLexer::from("x".chars()).peekable();
+        let typectx = Arc::new(RwLock::new(laddertypes::dict::TypeDict::new()));
+        let bindings = crate::parser::parse_binding_expr( &typectx, &mut lexer );
+
+        assert_eq!(
+            bindings,
+            Ok(crate::parser::VariableBinding::Atomic{
+                symbol: "x".into(),
+                typtag: None
+            })
+        );
+    }
+
+    #[test]
+    fn test_parse_typed_atomic_binding() {
+        let mut lexer = crate::lexer::LTIRLexer::from("x:T".chars()).peekable();
+        let typectx = Arc::new(RwLock::new(laddertypes::dict::TypeDict::new()));
+        let bindings = crate::parser::parse_binding_expr( &typectx, &mut lexer );
+
+        assert_eq!(
+            bindings,
+            Ok(crate::parser::VariableBinding::Atomic{
+                symbol: "x".into(),
+                typtag: Some(typectx.write().unwrap().parse("T").unwrap())
+            })
+        );
+    }
+
+    #[test]
+    fn test_parse_struct_binding() {
+        let mut lexer = crate::lexer::LTIRLexer::from("{x y}".chars()).peekable();
+        let typectx = Arc::new(RwLock::new(laddertypes::dict::TypeDict::new()));
+        let bindings = crate::parser::parse_binding_expr( &typectx, &mut lexer );
+
+        assert_eq!(
+            bindings,
+            Ok(crate::parser::VariableBinding::Struct{
+                members: vec![
+                    crate::parser::VariableBinding::Atomic{ symbol: "x".into(), typtag: None },                    
+                    crate::parser::VariableBinding::Atomic{ symbol: "y".into(), typtag: None }
+                ],
+                typtag: None
+            })
+        );
+    }
+
+    #[test]
+    fn test_parse_typed_struct_binding1() {
+        let mut lexer = crate::lexer::LTIRLexer::from("{x y}:T".chars()).peekable();
+        let typectx = Arc::new(RwLock::new(laddertypes::dict::TypeDict::new()));
+        let bindings = crate::parser::parse_binding_expr( &typectx, &mut lexer );
+
+        assert_eq!(
+            bindings,
+            Ok(crate::parser::VariableBinding::Struct{
+                members: vec![
+                    crate::parser::VariableBinding::Atomic{ symbol: "x".into(), typtag: None },                    
+                    crate::parser::VariableBinding::Atomic{ symbol: "y".into(), typtag: None }
+                ],
+                typtag: Some(typectx.write().unwrap().parse("T").unwrap())
+            })
+        );
+    }
+
+    #[test]
+    fn test_parse_typed_struct_binding2() {
+        let mut lexer = crate::lexer::LTIRLexer::from("{x:U; y}:T".chars()).peekable();
+        let typectx = Arc::new(RwLock::new(laddertypes::dict::TypeDict::new()));
+        let bindings = crate::parser::parse_binding_expr( &typectx, &mut lexer );
+
+        let type_u = typectx.write().unwrap().parse("U").unwrap();
+        let type_t = typectx.write().unwrap().parse("T").unwrap();
+
+        assert_eq!(
+            bindings,
+            Ok(crate::parser::VariableBinding::Struct{
+                members: vec![
+                    crate::parser::VariableBinding::Atomic{
+                        symbol: "x".into(),
+                        typtag: Some(type_u)
+                    },
+                    crate::parser::VariableBinding::Atomic{ symbol: "y".into(), typtag: None }
+                ],
+                typtag: Some(type_t)
+            })
+        );
+    }
+}