throw exception when call-ing a system instruction.

src/prolog/machine/machine_errors.rs

@@ -1,5 +1,4 @@
 use prolog::ast::*;
-use prolog::builtins::*;
 use prolog::machine::machine_state::*;
 use prolog::num::bigint::BigInt;
 
@@ -8,6 +7,94 @@ use std::rc::Rc;
 pub(super) type MachineError = Vec<HeapCellValue>;
 pub(super) type MachineStub = Vec<HeapCellValue>;
 
+// from 7.12.2 b) of 13211-1:1995
+#[derive(Clone, Copy)]
+pub enum ValidType {
+    Atom,
+    Atomic,
+    Byte,
+    Callable,
+    Character,
+    Compound,
+    Evaluable,
+    InByte,
+    InCharacter,
+    Integer,
+    List,
+    Number,
+    Pair,
+    PredicateIndicator,
+    Variable
+}
+
+impl ValidType {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            ValidType::Atom => "atom",
+            ValidType::Atomic => "atomic",
+            ValidType::Byte => "byte",
+            ValidType::Callable => "callable",
+            ValidType::Character => "character",
+            ValidType::Compound => "compound",
+            ValidType::Evaluable => "evaluable",
+            ValidType::InByte => "in_byte",
+            ValidType::InCharacter => "in_character",
+            ValidType::Integer => "integer",
+            ValidType::List => "list",
+            ValidType::Number => "number",
+            ValidType::Pair => "pair",
+            ValidType::PredicateIndicator => "predicate_indicator",
+            ValidType::Variable => "variable"
+        }
+    }
+}
+
+// from 7.12.2 f) of 13211-1:1995
+#[derive(Clone, Copy)]
+pub enum RepFlag {
+    Character,
+    CharacterCode,
+    InCharacterCode,
+    MaxArity,
+    MaxInteger,
+    MinInteger
+}
+
+impl RepFlag {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            RepFlag::Character => "character",
+            RepFlag::CharacterCode => "character_code",
+            RepFlag::InCharacterCode => "in_character_code",
+            RepFlag::MaxArity => "max_arity",
+            RepFlag::MaxInteger => "max_integer",
+            RepFlag::MinInteger => "min_integer"
+        }
+    }
+}
+
+// from 7.12.2 g) of 13211-1:1995
+#[derive(Clone, Copy)]
+pub enum EvalError {
+    FloatOverflow,
+    IntOverflow,
+    Undefined,
+    Underflow,
+    ZeroDivisor
+}
+
+impl EvalError {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            EvalError::FloatOverflow => "float_overflow",
+            EvalError::IntOverflow => "int_overflow",
+            EvalError::Undefined => "undefined",
+            EvalError::Underflow => "underflow",
+            EvalError::ZeroDivisor => "zero_divisor"
+        }
+    }
+}
+
 // used by '$skip_max_list'.
 pub(super) enum CycleSearchResult {
     EmptyList,
@@ -125,7 +212,7 @@ impl MachineState {
         let mut error_form = vec![HeapCellValue::NamedStr(2, clause_name!("error"), None),
                                   HeapCellValue::Addr(Addr::HeapCell(h + 3)),
                                   HeapCellValue::Addr(Addr::HeapCell(h + 3 + err.len()))];
-        
+
         error_form.extend(err.into_iter());
         error_form.extend(src.into_iter());
 
@@ -143,6 +230,6 @@ impl MachineState {
         self.registers[1] = Addr::HeapCell(h);
 
         self.set_ball();
-        self.unwind_stack();       
+        self.unwind_stack();
     }
 }