Support unary plus operation

3 files changed, 48 insertions, 1 deletions

diff --git a/include/elna/boot/ast.h b/include/elna/boot/ast.h
index 9d978a3..30bc7c3 100644
--- a/include/elna/boot/ast.h
+++ b/include/elna/boot/ast.h
@@ -51,7 +51,8 @@ namespace elna::boot
     {
         reference,
         negation,
-        minus
+        minus,
+        plus
     };
 
     class variable_declaration;
diff --git a/include/elna/boot/symbol.h b/include/elna/boot/symbol.h
index 216021e..194c1cd 100644
--- a/include/elna/boot/symbol.h
+++ b/include/elna/boot/symbol.h
@@ -475,6 +475,34 @@ namespace elna::boot
     bool is_primitive_type(const type& checked, const std::string& name);
 
     /**
+     * Checks whether the given type is a numeric primitive type
+     * (\c Int, \c Word, or \c Float).
+     *
+     * \param checked The type to check.
+     * \return Whether the type is a numeric primitive.
+     */
+    bool is_numeric_type(const type& checked);
+
+    /**
+     * Checks whether the given type is an integral primitive type
+     * (\c Int or \c Word).
+     *
+     * \param checked The type to check.
+     * \return Whether the type is an integral primitive.
+     */
+    bool is_integral_type(const type& checked);
+
+    /**
+     * Checks whether the given type is a discrete primitive type
+     * (\c Int, \c Word, \c Bool, or \c Char), i.e. a type with a
+     * finite range of ordered values suitable for \c \#min/\c \#max.
+     *
+     * \param checked The type to check.
+     * \return Whether the type is a discrete primitive.
+     */
+    bool is_discrete_type(const type& checked);
+
+    /**
      * Checks whether the given type is a pointer type.
      *
      * A pointer type is considered to be a variable pointer, a procedure
diff --git a/include/elna/boot/type_check.h b/include/elna/boot/type_check.h
index 5b6ed1c..8c7dd80 100644
--- a/include/elna/boot/type_check.h
+++ b/include/elna/boot/type_check.h
@@ -175,6 +175,23 @@ namespace elna::boot
     };
 
     /**
+     * A unary operator is applied to an unsupported type.
+     */
+    class unary_operation_error : public error
+    {
+        type actual;
+        unary_operator op;
+
+        static char unary_operator_symbol(unary_operator op);
+
+    public:
+        unary_operation_error(const source_position position, type actual,
+                unary_operator op);
+
+        std::string what() const override;
+    };
+
+    /**
      * Chain of responsibility for type compatibility checks.
      *
      * Populate \c ctx with pre-resolved types, then call \c run().
@@ -237,5 +254,6 @@ namespace elna::boot
         void visit(case_statement *statement) override;
         void visit(record_constructor_expression *expression) override;
         void visit(array_constructor_expression *expression) override;
+        void visit(unary_expression *expression) override;
     };
 }