feat(interface-types) Implement the string.size instruction.

src/decoders/binary.rs

@@ -219,6 +219,8 @@ fn instruction<'input, E: ParseError<&'input [u8]>>(
             )
         }
 
+        0x24 => (input, Instruction::StringSize),
+
         _ => return Err(Err::Error(make_error(input, ErrorKind::ParseTo))),
     })
 }
@@ -620,7 +622,7 @@ mod tests {
     #[test]
     fn test_instructions() {
         let input = &[
-            0x24, // list of 36 items
+            0x25, // list of 37 items
             0x00, 0x01, // ArgumentGet { index: 1 }
             0x01, 0x01, // CallCore { function_index: 1 }
             0x02, // S8FromI32
@@ -657,6 +659,7 @@ mod tests {
             0x21, // I64FromU64
             0x22, // StringLiftMemory
             0x23, 0x01, // StringLowerMemory { allocator_index: 1 }
+            0x24, // StringSize
             0x0a,
         ];
         let output = Ok((
@@ -698,6 +701,7 @@ mod tests {
                 Instruction::I64FromU64,
                 Instruction::StringLiftMemory,
                 Instruction::StringLowerMemory { allocator_index: 1 },
+                Instruction::StringSize,
             ],
         ));
 

src/decoders/wat.rs

@@ -62,6 +62,7 @@ mod keyword {
     custom_keyword!(i64_from_u64 = "i64.from_u64");
     custom_keyword!(string_lift_memory = "string.lift_memory");
     custom_keyword!(string_lower_memory = "string.lower_memory");
+    custom_keyword!(string_size = "string.size");
 }
 
 impl Parse<'_> for InterfaceType {
@@ -285,6 +286,10 @@ impl<'a> Parse<'a> for Instruction {
             Ok(Instruction::StringLowerMemory {
                 allocator_index: parser.parse()?,
             })
+        } else if lookahead.peek::<keyword::string_size>() {
+            parser.parse::<keyword::string_size>()?;
+
+            Ok(Instruction::StringSize)
         } else {
             Err(lookahead.error())
         }
@@ -666,6 +671,7 @@ mod tests {
             "i64.from_u64",
             "string.lift_memory",
             "string.lower_memory 42",
+            "string.size",
         ];
         let outputs = vec![
             Instruction::ArgumentGet { index: 7 },
@@ -706,6 +712,7 @@ mod tests {
             Instruction::StringLowerMemory {
                 allocator_index: 42,
             },
+            Instruction::StringSize,
         ];
 
         assert_eq!(inputs.len(), outputs.len());

src/encoders/binary.rs

@@ -299,6 +299,8 @@ where
                 0x23_u8.to_bytes(writer)?;
                 (*allocator_index as u64).to_bytes(writer)?;
             }
+
+            Instruction::StringSize => 0x24_u8.to_bytes(writer)?,
         }
 
         Ok(())
@@ -577,9 +579,10 @@ mod tests {
                 Instruction::I64FromU64,
                 Instruction::StringLiftMemory,
                 Instruction::StringLowerMemory { allocator_index: 1 },
+                Instruction::StringSize,
             ],
             &[
-                0x24, // list of 36 items
+                0x25, // list of 37 items
                 0x00, 0x01, // ArgumentGet { index: 1 }
                 0x01, 0x01, // CallCore { function_index: 1 }
                 0x02, // S8FromI32
@@ -616,6 +619,7 @@ mod tests {
                 0x21, // I64FromU64
                 0x22, // StringLiftMemory
                 0x23, 0x01, // StringLowerMemory { allocator_index: 1 }
+                0x24, // StringSize
             ]
         );
     }

src/encoders/wat.rs

@@ -121,6 +121,7 @@ impl ToString for &Instruction {
             Instruction::StringLowerMemory { allocator_index } => {
                 format!(r#"string.lower_memory {}"#, allocator_index)
             }
+            Instruction::StringSize => "string.size".into(),
         }
     }
 }
@@ -391,6 +392,7 @@ mod tests {
                 allocator_index: 42,
             })
                 .to_string(),
+            (&Instruction::StringSize).to_string(),
         ];
         let outputs = vec![
             "arg.get 7",
@@ -429,6 +431,7 @@ mod tests {
             "i64.from_u64",
             "string.lift_memory",
             "string.lower_memory 42",
+            "string.size",
         ];
 
         assert_eq!(inputs, outputs);

src/interpreter/instruction.rs

@@ -119,4 +119,7 @@ pub enum Instruction {
         /// The allocator function index.
         allocator_index: u32,
     },
+
+    /// The `string.size` instruction.
+    StringSize,
 }

src/interpreter/instructions/strings.rs

@@ -135,6 +135,34 @@ executable_instruction!(
     }
 );
 
+executable_instruction!(
+    string_size(instruction: Instruction) -> _ {
+        move |runtime| -> _ {
+            let value = runtime.stack.peek1().ok_or_else(|| {
+                InstructionError::new(
+                    instruction,
+                    InstructionErrorKind::StackIsTooSmall { needed: 1 },
+                )
+            })?;
+
+            if let InterfaceValue::String(string) = value {
+                let length = string.len() as i32;
+                runtime.stack.push(InterfaceValue::I32(length));
+
+                Ok(())
+            } else {
+                Err(InstructionError::new(
+                    instruction,
+                    InstructionErrorKind::InvalidValueOnTheStack {
+                        expected_type: InterfaceType::String,
+                        received_type: value.into(),
+                    }
+                ))
+            }
+        }
+    }
+);
+
 #[cfg(test)]
 mod tests {
     test_executable_instruction!(
@@ -323,4 +351,36 @@ mod tests {
             },
             error: r#"`string.lower_memory 153` the local or import function `153` has the signature `[I32] -> [I32]` but it received values of kind `[I32, I32] -> []`"#,
     );
+
+    test_executable_instruction!(
+        test_string_size =
+            instructions: [
+                Instruction::ArgumentGet { index: 0 },
+                Instruction::StringSize,
+            ],
+            invocation_inputs: [InterfaceValue::String("Hello, World!".into())],
+            instance: Instance::new(),
+            stack: [InterfaceValue::String("Hello, World!".into()), InterfaceValue::I32(13)],
+    );
+
+    test_executable_instruction!(
+        test_string_size__stack_is_too_small =
+            instructions: [
+                Instruction::StringSize,
+            ],
+            invocation_inputs: [],
+            instance: Instance::new(),
+            error: r#"`string.size` needed to read `1` value(s) from the stack, but it doesn't contain enough data"#,
+    );
+
+    test_executable_instruction!(
+        test_string_size__invalid_value_on_the_stack =
+            instructions: [
+                Instruction::ArgumentGet { index: 0 },
+                Instruction::StringSize,
+            ],
+            invocation_inputs: [InterfaceValue::I32(42)],
+            instance: Instance::new(),
+            error: r#"`string.size` read a value of type `I32` from the stack, but the type `String` was expected"#,
+    );
 }

src/interpreter/mod.rs

@@ -234,6 +234,7 @@ where
                 Instruction::StringLowerMemory { allocator_index } => {
                     instructions::string_lower_memory(*allocator_index, *instruction)
                 }
+                Instruction::StringSize => instructions::string_size(*instruction),
             })
             .collect();