From c41979400e65514a203049b6b5ce5c866a93a403 Mon Sep 17 00:00:00 2001
From: Ivan Enderlin <ivan.enderlin@hoa-project.net>
Date: Thu, 12 Mar 2020 14:39:15 +0100
Subject: [PATCH] feat(interface-types) Use include ranges to read the memory.

---
 .../instructions/memory_to_string.rs          | 28 +++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/interpreter/instructions/memory_to_string.rs b/src/interpreter/instructions/memory_to_string.rs
index f96c47f..e30b70c 100644
--- a/src/interpreter/instructions/memory_to_string.rs
+++ b/src/interpreter/instructions/memory_to_string.rs
@@ -31,7 +31,13 @@ executable_instruction!(
             let pointer = to_native::<i32>(&inputs[1], instruction)? as usize;
             let memory_view = memory.view();
 
-            if memory_view.len() < pointer + length {
+            if length == 0 {
+                runtime.stack.push(InterfaceValue::String("".into()));
+
+                return Ok(())
+            }
+
+            if memory_view.len() <= pointer + length - 1 {
                 return Err(InstructionError::new(
                     instruction,
                     InstructionErrorKind::MemoryOutOfBoundsAccess {
@@ -41,7 +47,7 @@ executable_instruction!(
                 ));
             }
 
-            let data: Vec<u8> = (&memory_view[pointer..pointer + length])
+            let data: Vec<u8> = (&memory_view[pointer..=pointer + length - 1])
                 .iter()
                 .map(Cell::get)
                 .collect();
@@ -78,6 +84,24 @@ mod tests {
             stack: [InterfaceValue::String("Hello, World!".into())],
     );
 
+    test_executable_instruction!(
+        test_memory_to_string__empty_string =
+            instructions: [
+                Instruction::ArgumentGet { index: 1 },
+                Instruction::ArgumentGet { index: 0 },
+                Instruction::MemoryToString,
+            ],
+            invocation_inputs: [
+                InterfaceValue::I32(0),
+                InterfaceValue::I32(0),
+            ],
+            instance: Instance {
+                memory: Memory::new(vec![]),
+                ..Default::default()
+            },
+            stack: [InterfaceValue::String("".into())],
+    );
+
     test_executable_instruction!(
         test_memory_to_string__read_out_of_memory =
             instructions: [