Emit error if parenthesis absent from declaration

Author: istathar

src/parsing/parser.rs

@@ -39,6 +39,7 @@ pub enum ParsingError {
     InvalidForma(usize),
     InvalidGenus(usize),
     InvalidSignature(usize),
+    InvalidParameters(usize),
     InvalidDeclaration(usize),
     InvalidSection(usize),
     InvalidInvocation(usize),
@@ -76,6 +77,7 @@ impl ParsingError {
             ParsingError::InvalidGenus(offset) => *offset,
             ParsingError::InvalidSignature(offset) => *offset,
             ParsingError::InvalidDeclaration(offset) => *offset,
+            ParsingError::InvalidParameters(offset) => *offset,
             ParsingError::InvalidSection(offset) => *offset,
             ParsingError::InvalidInvocation(offset) => *offset,
             ParsingError::InvalidFunction(offset) => *offset,
@@ -856,6 +858,23 @@ impl<'i> Parser<'i> {
 
             (name, parameters)
         } else {
+            // Check if the text contains multiple space-separated identifiers
+            // which would indicate parameters without parentheses
+            let words: Vec<&str> = text
+                .trim()
+                .split_whitespace()
+                .collect();
+            if words.len() > 1 {
+                // Check if all words look like valid identifiers
+                let all_valid_identifiers = words
+                    .iter()
+                    .all(|word| validate_identifier(word).is_some());
+
+                if all_valid_identifiers {
+                    return Err(ParsingError::InvalidParameters(self.offset));
+                }
+            }
+
             let name = validate_identifier(text).ok_or(ParsingError::InvalidIdentifier(
                 self.offset,
                 text.to_string(),

src/problem/messages.rs

@@ -350,6 +350,65 @@ Finally, variables can be assigned for the names of the input parameters:
                 .to_string(),
             )
         }
+        ParsingError::InvalidParameters(_) => {
+            let examples = vec![
+                Procedure {
+                    name: Identifier("create_bypass"),
+                    parameters: Some(vec![Identifier("a"), Identifier("b")]),
+                    signature: None,
+                    elements: Vec::new(),
+                },
+                Procedure {
+                    name: Identifier("bulldoze"),
+                    parameters: Some(vec![Identifier("c")]),
+                    signature: None,
+                    elements: Vec::new(),
+                },
+                Procedure {
+                    name: Identifier("lawsuit"),
+                    parameters: None,
+                    signature: Some(Signature {
+                        domain: Genus::Single(Forma("Council")),
+                        range: Genus::List(Forma("Penny")),
+                    }),
+                    elements: Vec::new(),
+                },
+                Procedure {
+                    name: Identifier("lawsuit"),
+                    parameters: Some(vec![Identifier("c")]),
+                    signature: Some(Signature {
+                        domain: Genus::Single(Forma("Council")),
+                        range: Genus::List(Forma("Penny")),
+                    }),
+                    elements: Vec::new(),
+                },
+            ];
+
+            (
+                "Parameters must be enclosed in parentheses".to_string(),
+                format!(
+                    r#"
+Parameters to a procedure must be variables, and enclosed in parentheses. For
+example:
+
+    {}
+    {}
+
+Naming the input genus is optional, however; these are both valid procedure
+declarations (and in fact the same):
+
+    {}
+    {}
+                    "#,
+                    examples[0].present(renderer),
+                    examples[1].present(renderer),
+                    examples[2].present(renderer),
+                    examples[3].present(renderer)
+                )
+                .trim_ascii()
+                .to_string(),
+            )
+        }
         ParsingError::InvalidSection(_) => {
             // Roman numeral sections don't have AST representation
             (

tests/broken/ParametersWithoutParentheses.tq

@@ -0,0 +1,10 @@
+% technique v1
+
+make_coffee beans water : Beans Water -> Coffee
+
+# Coffee making procedure
+This procedure demonstrates incorrect parameter syntax.
+
+1. Grind the beans.
+2. Heat the water.
+3. Brew the coffee.

tests/parsing/errors.rs

@@ -69,7 +69,7 @@ make-coffee : Ingredients -> Coffee
 make coffee : Ingredients -> Coffee
             "#
             .trim_ascii(),
-            ParsingError::InvalidIdentifier(0, "".to_string()),
+            ParsingError::InvalidParameters(0),
         );
     }