Add support for Array Type Checker

runtime/src/lib.rs

@@ -19,84 +19,143 @@
 
 // Rust Library
 
+use std::ffi::CStr;
 use std::mem;
 use std::os::raw::c_char;
 
-// String comparision
+pub fn compute_size(type_string: &str) -> i32 {
+    let mut bits = String::new();
+    //Index 2 and 3 represent the size
+    bits.push(type_string.chars().nth(2).unwrap());
+    bits.push(type_string.chars().nth(3).unwrap());
+    let total_bits: i32 = bits.parse().unwrap();
+    let mut length_bits = String::new();
+    let index = 4;
+    for i in 0..total_bits {
+        let iterator = i as usize;
+        length_bits.push(type_string.chars().nth(iterator + index).unwrap());
+    }
+    //Convert size to i32 for integer comparision
+    let size: i32 = length_bits.parse().unwrap();
+    return size;
+}
+
+pub fn calculate_type_priority(type_string: &str) -> i32 {
+    let mut priority = 0;
+    match type_string.chars().nth(1) {
+        Some('C') => priority = 4,
+        Some('B') => priority = 1,
+        Some('F') | Some('I') => priority = 8,
+        Some('A') => priority = 16,
+        _ => println!("Unsupported type"),
+    }
+    return priority;
+}
+
+/*
+ * Algorithm for checking whether typecast is possible from source to destination
+ * Index 0 - represents data structure
+ * Index 1 - represents type
+ * Index 2 and 3 - represents bits followed by its size
+ * */
 #[no_mangle]
-pub extern "C" fn is_same_type(src_type : *const c_char, dest_type : *const c_char) -> bool
-{
-  return src_type == dest_type;
+pub extern "C" fn is_same_type(src_type: *const c_char, dest_type: *const c_char) -> bool {
+    //Conversion to CStr
+    let source_cstr: &CStr = unsafe { CStr::from_ptr(src_type) };
+    let dest_cstr: &CStr = unsafe { CStr::from_ptr(dest_type) };
+    //Conversion to rust strings
+    let source: String = source_cstr.to_str().unwrap().to_owned();
+    let destination: String = dest_cstr.to_str().unwrap().to_owned();
+    //If type strings are same
+    if source == destination {
+        return true;
+    }
+    //Index 0 represents type of data structure
+    if source.chars().nth(0) != destination.chars().nth(0) {
+        return false;
+    }
+    let mut src_priority = 0;
+    let mut dest_priority = 0;
+    match source.chars().nth(0) {
+        Some('A') => {
+            if source.chars().nth(1) != destination.chars().nth(1) {
+                src_priority = calculate_type_priority(&source);
+                dest_priority = calculate_type_priority(&destination);
+            }
+            // If source type is bigger than destination, type cast is not possible
+            if src_priority > dest_priority {
+                return false;
+            }
+            let src_size: i32 = compute_size(&source);
+            let dest_size: i32 = compute_size(&destination);
+            if src_size > dest_size {
+                return false;
+            }
+        }
+        _ => println!("Unsupported data structure"),
+    }
+    //If all the checks are passed, type cast from source to destination is valid
+    return true;
 }
 
 // Prints 64 bit signed integer
 #[no_mangle]
-pub extern "C" fn print64(num64 : i64)
-{
-   println!("{}", num64);
+pub extern "C" fn print64(num64: i64) {
+    println!("{}", num64);
 }
 
 // Prints 32 bit signed integer
 #[no_mangle]
-pub extern "C" fn print32(num32 : i32)
-{
-   println!("{}", num32);
+pub extern "C" fn print32(num32: i32) {
+    println!("{}", num32);
 }
 
 // Prints 16 bit signed integer
 #[no_mangle]
-pub extern "C" fn print16(num16 : i16)
-{
-   println!("{}", num16);
+pub extern "C" fn print16(num16: i16) {
+    println!("{}", num16);
 }
 
 // Prints 8 bit signed integer
 #[no_mangle]
-pub extern "C" fn print8(num8 : i8)
-{
-   println!("{}", num8);
+pub extern "C" fn print8(num8: i8) {
+    println!("{}", num8);
 }
 
 // Prints 64 bit unsigned integer
 #[no_mangle]
-pub extern "C" fn printu64(num64 : u64)
-{
-   println!("{}", num64);
+pub extern "C" fn printu64(num64: u64) {
+    println!("{}", num64);
 }
 
 // Prints 32 bit unsigned integer
 #[no_mangle]
-pub extern "C" fn printu32(num32 : u32)
-{
-   println!("{}", num32);
+pub extern "C" fn printu32(num32: u32) {
+    println!("{}", num32);
 }
 
 // Prints 16 bit unsigned integer
 #[no_mangle]
-pub extern "C" fn printu16(num16 : u16)
-{
-   println!("{}", num16);
+pub extern "C" fn printu16(num16: u16) {
+    println!("{}", num16);
 }
 
 // Prints 8 bit unsigned integer
 #[no_mangle]
-pub extern "C" fn printu8(num8 : u8)
-{
-   println!("{}", num8);
+pub extern "C" fn printu8(num8: u8) {
+    println!("{}", num8);
 }
 
 // Prints 64 bit float
 #[no_mangle]
-pub extern "C" fn printf64(num64 : f64)
-{
-   println!("{}", num64);
+pub extern "C" fn printf64(num64: f64) {
+    println!("{}", num64);
 }
 
 // Prints 32 bit float
 #[no_mangle]
-pub extern "C" fn printf32(num32 : f32)
-{
-   println!("{}", num32);
+pub extern "C" fn printf32(num32: f32) {
+    println!("{}", num32);
 }
 
 #[no_mangle]
@@ -125,7 +184,7 @@ pub extern "C" fn int_array_store(arr_ptr: *mut Vec<*mut i32>, n: i32, ref_ptr:
 
 #[no_mangle]
 pub extern "C" fn int_array_load(arr_ptr: *mut Vec<*mut i32>, n: i32) -> *mut i32 {
-    let arr = unsafe { Box::from_raw(arr_ptr)};
+    let arr = unsafe { Box::from_raw(arr_ptr) };
     let n_size = n as usize;
     let return_val = arr[n_size];
     mem::forget(arr);