stdlib Vec (FuelLabs#1118)

* Add partial implementation.

* Fix offset calculation.

* memcopy when growing

* Add more methods.

* Fix copy bytes calculation.

* Update sway-lib-std/src/vec.sw

Co-authored-by: mitchmindtree <[email protected]>

* Add empty test.

* Add push functionality.

* Add get operation.

* Add test.

* Fix path to stdlib.

* Fix revert name.

* Minor fixes to vec + new test

* fmt

* Remove all asm blocks

* Additional clean up

* * Format the test and add JSON oracle
* Use size_of from the intrinsics library instead of __size_of

* remove unnecessary import

* remove unnecessary file

* Update sway-lib-std/src/vec.sw

Co-authored-by: Braqzen <[email protected]>

* Update sway-lib-std/src/vec.sw

Co-authored-by: Braqzen <[email protected]>

* first wave of comments

* Update test/src/e2e_vm_tests/test_programs/should_pass/stdlib/vec/src/main.sw

Co-authored-by: Braqzen <[email protected]>

* Update test/src/e2e_vm_tests/test_programs/should_pass/stdlib/vec/src/main.sw

Co-authored-by: Braqzen <[email protected]>

* wave 2 of comments

* revert the alphbeization of ptr and cap

* Address more comments

Co-authored-by: mitchmindtree <[email protected]>
Co-authored-by: Alex Hansen <[email protected]>
Co-authored-by: Mohammad Fawaz <[email protected]>
Co-authored-by: Braqzen <[email protected]>
Co-authored-by: Emily Herbert <[email protected]>

sway-lib-std/src/lib.sw

@@ -26,5 +26,6 @@ dep reentrancy;
 dep vm/mod;
 dep flags;
 dep u128;
+dep vec;
 
 use core::*;

sway-lib-std/src/vec.sw

@@ -0,0 +1,142 @@
+library vec;
+
+use ::alloc::{alloc, realloc};
+use ::intrinsics::size_of;
+use ::mem::{read, write};
+use ::option::Option;
+
+struct RawVec<T> {
+    ptr: u64,
+    cap: u64,
+}
+
+impl<T> RawVec<T> {
+    /// Create a new `RawVec` with zero capacity.
+    fn new() -> Self {
+        RawVec {
+            ptr: alloc(0),
+            cap: 0,
+        }
+    }
+
+    /// Creates a `RawVec` (on the heap) with exactly the capacity for a
+    /// `[T; capacity]`. This is equivalent to calling `RawVec::new` when
+    /// `capacity` is `0`.
+    fn with_capacity(capacity: u64) -> Self {
+        RawVec {
+            ptr: alloc(capacity * size_of::<T>()),
+            cap: capacity,
+        }
+    }
+
+    /// Gets the pointer of the allocation.
+    fn ptr(self) -> u64 {
+        self.ptr
+    }
+
+    /// Gets the capacity of the allocation.
+    fn capacity(self) -> u64 {
+        self.cap
+    }
+
+    /// Grow the capacity of the vector by doubling its current capacity. The
+    /// `realloc` function / allocates memory on the heap and copies the data
+    /// from the old allocation to the new allocation
+    fn grow(mut self) {
+        let new_cap = match self.cap {
+            0 => 1, _ => 2 * self.cap, 
+        };
+
+        self.ptr = realloc(self.ptr, self.cap * size_of::<T>(), new_cap * size_of::<T>());
+        self.cap = new_cap;
+    }
+}
+
+/// A contiguous growable array type, written as `Vec<T>`, short for 'vector'.
+pub struct Vec<T> {
+    buf: RawVec<T>,
+    len: u64,
+}
+
+impl<T> Vec<T> {
+    /// Constructs a new, empty `Vec<T>`.
+    ///
+    /// The vector will not allocate until elements are pushed onto it.
+    pub fn new() -> Self {
+        Vec {
+            buf: ~RawVec::new(),
+            len: 0,
+        }
+    }
+
+    /// Constructs a new, empty `Vec<T>` with the specified capacity.
+    ///
+    /// The vector will be able to hold exactly `capacity` elements without
+    /// reallocating. If `capacity` is 0, the vector will not allocate.
+    ///
+    /// It is important to note that although the returned vector has the
+    /// *capacity* specified, the vector will have a zero *length*.
+    pub fn with_capacity(capacity: u64) -> Self {
+        Vec {
+            buf: ~RawVec::with_capacity(capacity),
+            len: 0,
+        }
+    }
+
+    /// Appends an element to the back of a collection.
+    pub fn push(mut self, value: T) {
+        // If there is insufficient capacity, grow the buffer.
+        if self.len == self.buf.capacity() {
+            self.buf.grow();
+        };
+
+        // Get a pointer to the end of the buffer, where the new element will
+        // be inserted.
+        let end = self.buf.ptr() + self.len * size_of::<T>();
+
+        // Write `value` at pointer `end`
+        write(end, value);
+
+        // Increment length.
+        self.len = self.len + 1;
+    }
+
+    /// Gets the capacity of the allocation.
+    pub fn capacity(self) -> u64 {
+        self.buf.cap
+    }
+
+    /// Clears the vector, removing all values.
+    ///
+    /// Note that this method has no effect on the allocated capacity
+    /// of the vector.
+    pub fn clear(mut self) {
+        self.len = 0;
+    }
+
+    /// Returns a vector element at `index`, or None if `index` is out of
+    /// bounds.
+    pub fn get(self, index: u64) -> Option<T> {
+        // First check that index is within bounds.
+        if self.len <= index {
+            return Option::None::<T>();
+        };
+
+        // Get a pointer to the desired element using `index`
+        let ptr = self.buf.ptr() + index * size_of::<T>();
+
+        // Read from `ptr`
+        Option::Some(read(ptr))
+    }
+
+    /// Returns the number of elements in the vector, also referred to
+    /// as its 'length'.
+    pub fn len(self) -> u64 {
+        self.len
+    }
+
+    /// Returns `true` if the vector contains no elements.
+    pub fn is_empty(self) -> bool {
+        self.len == 0
+    }
+}

test/src/e2e_vm_tests/mod.rs

@@ -222,6 +222,7 @@ pub fn run(locked: bool, filter_regex: Option<regex::Regex>) {
         ),
         ("should_pass/stdlib/b512_test", ProgramState::Return(1)), // true
         ("should_pass/stdlib/block_height", ProgramState::Return(1)), // true
+        ("should_pass/stdlib/vec", ProgramState::Return(1)),       // true
         (
             "should_pass/language/trait_override_bug",
             ProgramState::Return(7),

test/src/e2e_vm_tests/test_programs/should_pass/stdlib/vec/Forc.lock

@@ -0,0 +1,14 @@
+[[package]]
+name = 'core'
+source = 'path+from-root-E8B33641BFB485A7'
+dependencies = []
+
+[[package]]
+name = 'std'
+source = 'path+from-root-E8B33641BFB485A7'
+dependencies = ['core']
+
+[[package]]
+name = 'vec'
+source = 'root'
+dependencies = ['std']

test/src/e2e_vm_tests/test_programs/should_pass/stdlib/vec/Forc.toml

@@ -0,0 +1,8 @@
+[project]
+authors = ["Fuel Labs <[email protected]>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "vec"
+
+[dependencies]
+std = { path = "../../../../../../../sway-lib-std" }

test/src/e2e_vm_tests/test_programs/should_pass/stdlib/vec/json_abi_oracle.json

@@ -0,0 +1,14 @@
+[
+  {
+    "inputs": [],
+    "name": "main",
+    "outputs": [
+      {
+        "components": null,
+        "name": "",
+        "type": "bool"
+      }
+    ],
+    "type": "function"
+  }
+]