lang: Zero copy deserialization (#202)

.travis.yml

@@ -19,7 +19,7 @@ _examples: &examples
   - npm install -g mocha
   - npm install -g ts-mocha
   - npm install -g typescript
-  - npm install -g @project-serum/anchor
+  - cd ts && yarn && yarn build && npm link && cd ../
   - npm install -g @project-serum/serum
   - npm install -g @project-serum/common
   - npm install -g @solana/spl-token
@@ -28,7 +28,7 @@ _examples: &examples
   - export PATH="/home/travis/.local/share/solana/install/active_release/bin:$PATH"
   - export NODE_PATH="/home/travis/.nvm/versions/node/v$NODE_VERSION/lib/node_modules/:$NODE_PATH"
   - yes | solana-keygen new
-  - cargo install --git https://github.com/project-serum/anchor anchor-cli --locked
+  - cargo install --path $TRAVIS_BUILD_DIR/cli anchor-cli --locked
 
 jobs:
   include:
@@ -59,6 +59,7 @@ jobs:
         - pushd examples/events && anchor test && popd
         - pushd examples/cashiers-check && anchor test && popd
         - pushd examples/typescript && yarn && anchor test && popd
+        - pushd examples/zero-copy && yarn && anchor test && popd
     - <<: *examples
       name: Runs the examples 2
       script:

CHANGELOG.md

@@ -14,6 +14,8 @@ incremented for features.
 ## Features
 
 * lang: Allows one to specify multiple `with` targets when creating associated acconts ([#197](https://github.com/project-serum/anchor/pull/197)).
+* lang, ts: Add array support ([#202](https://github.com/project-serum/anchor/pull/202)).
+* lang: Zero copy deserialization for accounts ([#202](https://github.com/project-serum/anchor/pull/202)).
 
 ## [0.4.3] - 2021-04-13
 

Cargo.lock

@@ -181,6 +181,7 @@ dependencies = [
  "anchor-derive-accounts",
  "base64 0.13.0",
  "borsh",
+ "bytemuck",
  "solana-program",
  "thiserror",
 ]
@@ -451,6 +452,12 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e3b5ca7a04898ad4bcd41c90c5285445ff5b791899bb1b0abdd2a2aa791211d7"
 
+[[package]]
+name = "bytemuck"
+version = "1.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bed57e2090563b83ba8f83366628ce535a7584c9afa4c9fc0612a03925c6df58"
+
 [[package]]
 name = "byteorder"
 version = "1.3.4"

examples/zero-copy/Anchor.toml

@@ -0,0 +1,2 @@
+cluster = "localnet"
+wallet = "~/.config/solana/id.json"

examples/zero-copy/Cargo.toml

@@ -0,0 +1,4 @@
+[workspace]
+members = [
+    "programs/*"
+]

examples/zero-copy/migrations/deploy.js

@@ -0,0 +1,12 @@
+// Migrations are an early feature. Currently, they're nothing more than this
+// single deploy script that's invoked from the CLI, injecting a provider
+// configured from the workspace's Anchor.toml.
+
+const anchor = require("@project-serum/anchor");
+
+module.exports = async function (provider) {
+  // Configure client to use the provider.
+  anchor.setProvider(provider);
+
+  // Add your deploy script here.
+}

examples/zero-copy/programs/zero-copy/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "zero-copy"
+version = "0.1.0"
+description = "Created with Anchor"
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib", "lib"]
+name = "zero_copy"
+
+[features]
+no-entrypoint = []
+no-idl = []
+cpi = ["no-entrypoint"]
+default = []
+
+[dependencies]
+anchor-lang = { path = "../../../../lang" }

examples/zero-copy/programs/zero-copy/Xargo.toml

@@ -0,0 +1,2 @@
+[target.bpfel-unknown-unknown.dependencies.std]
+features = []

examples/zero-copy/programs/zero-copy/src/lib.rs

@@ -0,0 +1,144 @@
+//! This example demonstrates the use of zero copy deserialization for accounts.
+//! The main noticeable benefit one achieves using zero copy is the ability
+//! to create accounts larger than the size of the stack or heap, as is
+//! demonstrated by the event queue in this example.
+
+use anchor_lang::prelude::*;
+
+#[program]
+pub mod zero_copy {
+    use super::*;
+
+    pub fn create_foo(ctx: Context<CreateFoo>) -> ProgramResult {
+        let foo = &mut ctx.accounts.foo.load_init()?;
+        foo.authority = *ctx.accounts.authority.key;
+        foo.set_second_authority(ctx.accounts.authority.key);
+        Ok(())
+    }
+
+    pub fn update_foo(ctx: Context<UpdateFoo>, data: u64) -> ProgramResult {
+        let mut foo = ctx.accounts.foo.load_mut()?;
+        foo.data = data;
+        Ok(())
+    }
+
+    pub fn update_foo_second(ctx: Context<UpdateFooSecond>, second_data: u64) -> ProgramResult {
+        let mut foo = ctx.accounts.foo.load_mut()?;
+        foo.second_data = second_data;
+        Ok(())
+    }
+
+    pub fn create_bar(ctx: Context<CreateBar>) -> ProgramResult {
+        let bar = &mut ctx.accounts.bar.load_init()?;
+        bar.authority = *ctx.accounts.authority.key;
+        Ok(())
+    }
+
+    pub fn update_bar(ctx: Context<UpdateBar>, data: u64) -> ProgramResult {
+        let bar = &mut ctx.accounts.bar.load_mut()?;
+        bar.data = data;
+        Ok(())
+    }
+
+    pub fn create_large_account(_ctx: Context<CreateLargeAccount>) -> ProgramResult {
+        Ok(())
+    }
+
+    pub fn update_large_account(
+        ctx: Context<UpdateLargeAccount>,
+        idx: u32,
+        data: u64,
+    ) -> ProgramResult {
+        let event_q = &mut ctx.accounts.event_q.load_mut()?;
+        event_q.events[idx as usize] = Event {
+            data,
+            from: *ctx.accounts.from.key,
+        };
+        Ok(())
+    }
+}
+
+#[derive(Accounts)]
+pub struct CreateFoo<'info> {
+    #[account(init)]
+    foo: Loader<'info, Foo>,
+    #[account(signer)]
+    authority: AccountInfo<'info>,
+    rent: Sysvar<'info, Rent>,
+}
+
+#[derive(Accounts)]
+pub struct UpdateFoo<'info> {
+    #[account(mut, has_one = authority)]
+    foo: Loader<'info, Foo>,
+    #[account(signer)]
+    authority: AccountInfo<'info>,
+}
+
+#[derive(Accounts)]
+pub struct UpdateFooSecond<'info> {
+    #[account(mut, "&foo.load()?.get_second_authority() == second_authority.key")]
+    foo: Loader<'info, Foo>,
+    #[account(signer)]
+    second_authority: AccountInfo<'info>,
+}
+
+#[derive(Accounts)]
+pub struct CreateBar<'info> {
+    #[account(associated = authority, with = foo)]
+    bar: Loader<'info, Bar>,
+    #[account(signer)]
+    authority: AccountInfo<'info>,
+    foo: Loader<'info, Foo>,
+    rent: Sysvar<'info, Rent>,
+    system_program: AccountInfo<'info>,
+}
+
+#[derive(Accounts)]
+pub struct UpdateBar<'info> {
+    #[account(mut, has_one = authority)]
+    bar: Loader<'info, Bar>,
+    #[account(signer)]
+    authority: AccountInfo<'info>,
+}
+
+#[derive(Accounts)]
+pub struct CreateLargeAccount<'info> {
+    #[account(init)]
+    event_q: Loader<'info, EventQ>,
+    rent: Sysvar<'info, Rent>,
+}
+
+#[derive(Accounts)]
+pub struct UpdateLargeAccount<'info> {
+    #[account(mut)]
+    event_q: Loader<'info, EventQ>,
+    #[account(signer)]
+    from: AccountInfo<'info>,
+}
+
+#[account(zero_copy)]
+pub struct Foo {
+    pub authority: Pubkey,
+    pub data: u64,
+    pub second_data: u64,
+    #[accessor(Pubkey)] // The `accessor` api will likely be removed.
+    pub second_authority: [u8; 32],
+}
+
+#[associated(zero_copy)]
+pub struct Bar {
+    pub authority: Pubkey,
+    pub data: u64,
+}
+
+#[account(zero_copy)]
+pub struct EventQ {
+    pub events: [Event; 25000],
+}
+
+#[zero_copy]
+pub struct Event {
+    pub from: Pubkey,
+    pub data: u64,
+}

examples/zero-copy/tests/zero-copy.js

@@ -0,0 +1,229 @@
+const anchor = require("@project-serum/anchor");
+const assert = require("assert");
+
+describe("zero-copy", () => {
+  // Configure the client to use the local cluster.
+  anchor.setProvider(anchor.Provider.env());
+
+  const program = anchor.workspace.ZeroCopy;
+
+  const foo = new anchor.web3.Account();
+
+  it("Is creates a zero copy account", async () => {
+    await program.rpc.createFoo({
+      accounts: {
+        foo: foo.publicKey,
+        authority: program.provider.wallet.publicKey,
+        rent: anchor.web3.SYSVAR_RENT_PUBKEY,
+      },
+      instructions: [await program.account.foo.createInstruction(foo)],
+      signers: [foo],
+    });
+    const account = await program.account.foo(foo.publicKey);
+    assert.ok(
+      JSON.stringify(account.authority.toBuffer()) ===
+        JSON.stringify(program.provider.wallet.publicKey.toBuffer())
+    );
+    assert.ok(account.data.toNumber() === 0);
+    assert.ok(account.secondData.toNumber() === 0);
+    assert.ok(
+      JSON.stringify(account.secondAuthority) ===
+        JSON.stringify([...program.provider.wallet.publicKey.toBuffer()])
+    );
+  });
+
+  it("Updates a zero copy account field", async () => {
+    await program.rpc.updateFoo(new anchor.BN(1234), {
+      accounts: {
+        foo: foo.publicKey,
+        authority: program.provider.wallet.publicKey,
+      },
+    });
+
+    const account = await program.account.foo(foo.publicKey);
+
+    assert.ok(
+      JSON.stringify(account.authority.toBuffer()) ===
+        JSON.stringify(program.provider.wallet.publicKey.toBuffer())
+    );
+    assert.ok(account.data.toNumber() === 1234);
+    assert.ok(account.secondData.toNumber() === 0);
+    assert.ok(
+      JSON.stringify(account.secondAuthority) ===
+        JSON.stringify([...program.provider.wallet.publicKey.toBuffer()])
+    );
+  });
+
+  it("Updates a a second zero copy account field", async () => {
+    await program.rpc.updateFooSecond(new anchor.BN(55), {
+      accounts: {
+        foo: foo.publicKey,
+        secondAuthority: program.provider.wallet.publicKey,
+      },
+    });
+
+    const account = await program.account.foo(foo.publicKey);
+
+    assert.ok(
+      JSON.stringify(account.authority.toBuffer()) ===
+        JSON.stringify(program.provider.wallet.publicKey.toBuffer())
+    );
+    assert.ok(account.data.toNumber() === 1234);
+    assert.ok(account.secondData.toNumber() === 55);
+    assert.ok(
+      JSON.stringify(account.secondAuthority) ===
+        JSON.stringify([...program.provider.wallet.publicKey.toBuffer()])
+    );
+  });
+
+  it("Creates an associated zero copy account", async () => {
+    await program.rpc.createBar({
+      accounts: {
+        bar: await program.account.bar.associatedAddress(
+          program.provider.wallet.publicKey,
+          foo.publicKey
+        ),
+        authority: program.provider.wallet.publicKey,
+        foo: foo.publicKey,
+        rent: anchor.web3.SYSVAR_RENT_PUBKEY,
+        systemProgram: anchor.web3.SystemProgram.programId,
+      },
+    });
+
+    const bar = await program.account.bar.associated(
+      program.provider.wallet.publicKey,
+      foo.publicKey
+    );
+    assert.ok(bar.authority.equals(program.provider.wallet.publicKey));
+    assert.ok(bar.data.toNumber() === 0);
+  });
+
+  it("Updates an associated zero copy account", async () => {
+    await program.rpc.updateBar(new anchor.BN(99), {
+      accounts: {
+        bar: await program.account.bar.associatedAddress(
+          program.provider.wallet.publicKey,
+          foo.publicKey
+        ),
+        authority: program.provider.wallet.publicKey,
+      },
+    });
+    const bar = await program.account.bar.associated(
+      program.provider.wallet.publicKey,
+      foo.publicKey
+    );
+    assert.ok(bar.authority.equals(program.provider.wallet.publicKey));
+    assert.ok(bar.data.toNumber() === 99);
+  });
+
+  const eventQ = new anchor.web3.Account();
+  const size = 1000000 + 8; // Account size in bytes.
+
+  it("Creates a large event queue", async () => {
+    await program.rpc.createLargeAccount({
+      accounts: {
+        eventQ: eventQ.publicKey,
+        rent: anchor.web3.SYSVAR_RENT_PUBKEY,
+      },
+      instructions: [
+        await program.account.eventQ.createInstruction(eventQ, size),
+      ],
+      signers: [eventQ],
+    });
+    const account = await program.account.eventQ(eventQ.publicKey);
+    assert.ok(account.events.length === 25000);
+    account.events.forEach((event) => {
+      assert.ok(event.from.equals(new anchor.web3.PublicKey()));
+      assert.ok(event.data.toNumber() === 0);
+    });
+  });
+
+  it("Updates a large event queue", async () => {
+    // Set index 0.
+    await program.rpc.updateLargeAccount(0, new anchor.BN(48), {
+      accounts: {
+        eventQ: eventQ.publicKey,
+        from: program.provider.wallet.publicKey,
+      },
+    });
+    // Verify update.
+    let account = await program.account.eventQ(eventQ.publicKey);
+    assert.ok(account.events.length === 25000);
+    account.events.forEach((event, idx) => {
+      if (idx === 0) {
+        assert.ok(event.from.equals(program.provider.wallet.publicKey));
+        assert.ok(event.data.toNumber() === 48);
+      } else {
+        assert.ok(event.from.equals(new anchor.web3.PublicKey()));
+        assert.ok(event.data.toNumber() === 0);
+      }
+    });
+
+    // Set index 11111.
+    await program.rpc.updateLargeAccount(11111, new anchor.BN(1234), {
+      accounts: {
+        eventQ: eventQ.publicKey,
+        from: program.provider.wallet.publicKey,
+      },
+    });
+    // Verify update.
+    account = await program.account.eventQ(eventQ.publicKey);
+    assert.ok(account.events.length === 25000);
+    account.events.forEach((event, idx) => {
+      if (idx === 0) {
+        assert.ok(event.from.equals(program.provider.wallet.publicKey));
+        assert.ok(event.data.toNumber() === 48);
+      } else if (idx === 11111) {
+        assert.ok(event.from.equals(program.provider.wallet.publicKey));
+        assert.ok(event.data.toNumber() === 1234);
+      } else {
+        assert.ok(event.from.equals(new anchor.web3.PublicKey()));
+        assert.ok(event.data.toNumber() === 0);
+      }
+    });
+
+    // Set last index.
+    await program.rpc.updateLargeAccount(24999, new anchor.BN(99), {
+      accounts: {
+        eventQ: eventQ.publicKey,
+        from: program.provider.wallet.publicKey,
+      },
+    });
+    // Verify update.
+    account = await program.account.eventQ(eventQ.publicKey);
+    assert.ok(account.events.length === 25000);
+    account.events.forEach((event, idx) => {
+      if (idx === 0) {
+        assert.ok(event.from.equals(program.provider.wallet.publicKey));
+        assert.ok(event.data.toNumber() === 48);
+      } else if (idx === 11111) {
+        assert.ok(event.from.equals(program.provider.wallet.publicKey));
+        assert.ok(event.data.toNumber() === 1234);
+      } else if (idx === 24999) {
+        assert.ok(event.from.equals(program.provider.wallet.publicKey));
+        assert.ok(event.data.toNumber() === 99);
+      } else {
+        assert.ok(event.from.equals(new anchor.web3.PublicKey()));
+        assert.ok(event.data.toNumber() === 0);
+      }
+    });
+  });
+
+  it("Errors when setting an out of bounds index", async () => {
+    // Fail to set non existing index.
+    await assert.rejects(
+      async () => {
+        await program.rpc.updateLargeAccount(25000, new anchor.BN(1), {
+          accounts: {
+            eventQ: eventQ.publicKey,
+            from: program.provider.wallet.publicKey,
+          },
+        });
+      },
+      (err) => {
+        console.log("err", err);
+        return true;
+      }
+    );
+  });
+});

lang/Cargo.toml

@@ -18,9 +18,10 @@ anchor-attribute-error = { path = "./attribute/error", version = "0.4.3" }
 anchor-attribute-program = { path = "./attribute/program", version = "0.4.3" }
 anchor-attribute-state = { path = "./attribute/state", version = "0.4.3" }
 anchor-attribute-interface = { path = "./attribute/interface", version = "0.4.3" }
-anchor-derive-accounts = { path = "./derive/accounts", version = "0.4.3" }
 anchor-attribute-event = { path = "./attribute/event", version = "0.4.3" }
+anchor-derive-accounts = { path = "./derive/accounts", version = "0.4.3" }
+base64 = "0.13.0"
 borsh = "0.8.2"
+bytemuck = "1.4.0"
 solana-program = "1.6.3"
 thiserror = "1.0.20"
-base64 = "0.13.0"

lang/attribute/account/src/lib.rs

@@ -17,12 +17,39 @@ use syn::parse_macro_input;
 /// As a result, any calls to `AccountDeserialize`'s `try_deserialize` will
 /// check this discriminator. If it doesn't match, an invalid account was given,
 /// and the account deserialization will exit with an error.
+///
+/// # Zero Copy Deserialization
+///
+/// To enable zero-copy-deserialization, one can pass in the `zero_copy`
+/// argument to the macro as follows:
+///
+/// ```ignore
+/// #[account(zero_copy)]
+/// ```
+///
+/// This can be used to conveniently implement
+/// [`ZeroCopy`](./trait.ZeroCopy.html) so that the account can be used
+/// with [`AccountLoader`](./struct.AccountLoader.html).
+///
+/// Other than being more efficient, the most salient benefit this provides is
+/// the ability to define account types larger than the max stack or heap size.
+/// This is used in special cases, for example, the Serum DEX event queue. When
+/// using borsh, one is limited, since the account has to be copied and
+/// deserialized into a new data structure. With zero copy deserialization,
+/// everything is, effectively, lazy loaded on field access.
 #[proc_macro_attribute]
 pub fn account(
     args: proc_macro::TokenStream,
     input: proc_macro::TokenStream,
 ) -> proc_macro::TokenStream {
     let namespace = args.to_string().replace("\"", "");
+    let is_zero_copy = match args.into_iter().next() {
+        None => false,
+        Some(tt) => match tt {
+            proc_macro::TokenTree::Literal(_) => false,
+            _ => namespace == "zero_copy",
+        },
+    };
 
     let account_strct = parse_macro_input!(input as syn::ItemStruct);
     let account_name = &account_strct.ident;
@@ -30,7 +57,8 @@ pub fn account(
     let discriminator: proc_macro2::TokenStream = {
         // Namespace the discriminator to prevent collisions.
         let discriminator_preimage = {
-            if namespace.is_empty() {
+            // For now, zero copy accounts can't be namespaced.
+            if is_zero_copy || namespace.is_empty() {
                 format!("account:{}", account_name.to_string())
             } else {
                 format!("{}:{}", namespace, account_name.to_string())
@@ -44,61 +72,111 @@ pub fn account(
         format!("{:?}", discriminator).parse().unwrap()
     };
 
-    let coder = quote! {
-        impl anchor_lang::AccountSerialize for #account_name {
-            fn try_serialize<W: std::io::Write>(&self, writer: &mut W) -> std::result::Result<(), ProgramError> {
-                writer.write_all(&#discriminator).map_err(|_| ProgramError::InvalidAccountData)?;
-                AnchorSerialize::serialize(
-                    self,
-                    writer
-                )
-                    .map_err(|_| ProgramError::InvalidAccountData)?;
-                Ok(())
-            }
-        }
+    proc_macro::TokenStream::from({
+        if is_zero_copy {
+            quote! {
+                #[zero_copy]
+                #account_strct
 
-        impl anchor_lang::AccountDeserialize for #account_name {
-            fn try_deserialize(buf: &mut &[u8]) -> std::result::Result<Self, ProgramError> {
-                 if buf.len() < #discriminator.len() {
-                    return Err(ProgramError::AccountDataTooSmall);
+                unsafe impl anchor_lang::__private::bytemuck::Pod for #account_name {}
+                unsafe impl anchor_lang::__private::bytemuck::Zeroable for #account_name {}
+
+                impl anchor_lang::ZeroCopy for #account_name {}
+
+                impl anchor_lang::Discriminator for #account_name {
+                    fn discriminator() -> [u8; 8] {
+                        #discriminator
+                    }
                 }
-                let given_disc = &buf[..8];
-                if &#discriminator != given_disc {
-                    return Err(ProgramError::InvalidInstructionData);
+
+                // This trait is useful for clients deserializing accounts.
+                // It's expected on-chain programs deserialize via zero-copy.
+                impl anchor_lang::AccountDeserialize for #account_name {
+                    fn try_deserialize(buf: &mut &[u8]) -> std::result::Result<Self, ProgramError> {
+                        if buf.len() < #discriminator.len() {
+                            return Err(ProgramError::AccountDataTooSmall);
+                        }
+                        let given_disc = &buf[..8];
+                        if &#discriminator != given_disc {
+                            return Err(ProgramError::InvalidInstructionData);
+                        }
+                        Self::try_deserialize_unchecked(buf)
+                    }
+
+                    fn try_deserialize_unchecked(buf: &mut &[u8]) -> std::result::Result<Self, ProgramError> {
+                        let data: &[u8] = &buf[8..];
+                        // Re-interpret raw bytes into the POD data structure.
+                        let account = anchor_lang::__private::bytemuck::from_bytes(data);
+                        // Copy out the bytes into a new, owned data structure.
+                        Ok(*account)
+                    }
                 }
-                Self::try_deserialize_unchecked(buf)
             }
+        } else {
+            quote! {
+                #[derive(AnchorSerialize, AnchorDeserialize, Clone)]
+                #account_strct
 
-            fn try_deserialize_unchecked(buf: &mut &[u8]) -> std::result::Result<Self, ProgramError> {
-                let mut data: &[u8] = &buf[8..];
-                AnchorDeserialize::deserialize(&mut data)
-                    .map_err(|_| ProgramError::InvalidAccountData)
+                impl anchor_lang::AccountSerialize for #account_name {
+                    fn try_serialize<W: std::io::Write>(&self, writer: &mut W) -> std::result::Result<(), ProgramError> {
+                        writer.write_all(&#discriminator).map_err(|_| ProgramError::InvalidAccountData)?;
+                        AnchorSerialize::serialize(
+                            self,
+                            writer
+                        )
+                            .map_err(|_| ProgramError::InvalidAccountData)?;
+                        Ok(())
+                    }
+                }
+
+                impl anchor_lang::AccountDeserialize for #account_name {
+                    fn try_deserialize(buf: &mut &[u8]) -> std::result::Result<Self, ProgramError> {
+                        if buf.len() < #discriminator.len() {
+                            return Err(ProgramError::AccountDataTooSmall);
+                        }
+                        let given_disc = &buf[..8];
+                        if &#discriminator != given_disc {
+                            return Err(ProgramError::InvalidInstructionData);
+                        }
+                        Self::try_deserialize_unchecked(buf)
+                    }
+
+                    fn try_deserialize_unchecked(buf: &mut &[u8]) -> std::result::Result<Self, ProgramError> {
+                        let mut data: &[u8] = &buf[8..];
+                        AnchorDeserialize::deserialize(&mut data)
+                            .map_err(|_| ProgramError::InvalidAccountData)
+                    }
+                }
+
+                impl anchor_lang::Discriminator for #account_name {
+                    fn discriminator() -> [u8; 8] {
+                        #discriminator
+                    }
+                }
             }
         }
-
-        impl anchor_lang::Discriminator for #account_name {
-            fn discriminator() -> [u8; 8] {
-                #discriminator
-            }
-        }
-    };
-
-    proc_macro::TokenStream::from(quote! {
-        #[derive(AnchorSerialize, AnchorDeserialize, Clone)]
-        #account_strct
-
-        #coder
     })
 }
 
-/// Extends the `#[account]` attribute to allow one to create associated token
+/// Extends the `#[account]` attribute to allow one to create associated
 /// accounts. This includes a `Default` implementation, which means all fields
 /// in an `#[associated]` struct must implement `Default` and an
 /// `anchor_lang::Bump` trait implementation, which allows the account to be
 /// used as a program derived address.
+///
+/// # Zero Copy Deserialization
+///
+/// Similar to the `#[account]` attribute one can enable zero copy
+/// deserialization by using the `zero_copy` argument:
+///
+/// ```ignore
+/// #[associated(zero_copy)]
+/// ```
+///
+/// For more, see the [`account`](./attr.account.html) attribute.
 #[proc_macro_attribute]
 pub fn associated(
-    _args: proc_macro::TokenStream,
+    args: proc_macro::TokenStream,
     input: proc_macro::TokenStream,
 ) -> proc_macro::TokenStream {
     let mut account_strct = parse_macro_input!(input as syn::ItemStruct);
@@ -132,8 +210,9 @@ pub fn associated(
         _ => panic!("Fields must be named"),
     }
 
+    let args: proc_macro2::TokenStream = args.into();
     proc_macro::TokenStream::from(quote! {
-        #[anchor_lang::account]
+        #[anchor_lang::account(#args)]
         #[derive(Default)]
         #account_strct
 
@@ -144,3 +223,87 @@ pub fn associated(
         }
     })
 }
+
+#[proc_macro_derive(ZeroCopyAccessor, attributes(accessor))]
+pub fn derive_zero_copy_accessor(item: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    let account_strct = parse_macro_input!(item as syn::ItemStruct);
+    let account_name = &account_strct.ident;
+
+    let fields = match &account_strct.fields {
+        syn::Fields::Named(n) => n,
+        _ => panic!("Fields must be named"),
+    };
+    let methods: Vec<proc_macro2::TokenStream> = fields
+        .named
+        .iter()
+        .filter_map(|field: &syn::Field| {
+            field
+                .attrs
+                .iter()
+                .filter(|attr| {
+                    let name = anchor_syn::parser::tts_to_string(&attr.path);
+                    if name != "accessor" {
+                        return false;
+                    }
+                    return true;
+                })
+                .next()
+                .map(|attr| {
+                    let mut tts = attr.tokens.clone().into_iter();
+                    let g_stream = match tts.next().expect("Must have a token group") {
+                        proc_macro2::TokenTree::Group(g) => g.stream(),
+                        _ => panic!("Invalid syntax"),
+                    };
+                    let accessor_ty = match g_stream.into_iter().next() {
+                        Some(token) => token,
+                        _ => panic!("Missing accessor type"),
+                    };
+
+                    let field_name = field.ident.as_ref().unwrap();
+
+                    let get_field: proc_macro2::TokenStream =
+                        format!("get_{}", field_name.to_string()).parse().unwrap();
+                    let set_field: proc_macro2::TokenStream =
+                        format!("set_{}", field_name.to_string()).parse().unwrap();
+
+                    quote! {
+                        pub fn #get_field(&self) -> #accessor_ty {
+                            anchor_lang::__private::ZeroCopyAccessor::get(&self.#field_name)
+                        }
+                        pub fn #set_field(&mut self, input: &#accessor_ty) {
+                            self.#field_name = anchor_lang::__private::ZeroCopyAccessor::set(input);
+                        }
+                    }
+                })
+        })
+        .collect();
+    proc_macro::TokenStream::from(quote! {
+        impl #account_name {
+            #(#methods)*
+        }
+    })
+}
+
+/// A data structure that can be used as an internal field for a zero copy
+/// deserialized account, i.e., a struct marked with `#[account(zero_copy)]`.
+///
+/// This is just a convenient alias for
+///
+/// ```ignore
+/// #[derive(Copy, Clone)]
+/// #[repr(packed)]
+/// struct MyStruct {...}
+/// ```
+#[proc_macro_attribute]
+pub fn zero_copy(
+    _args: proc_macro::TokenStream,
+    item: proc_macro::TokenStream,
+) -> proc_macro::TokenStream {
+    let account_strct = parse_macro_input!(item as syn::ItemStruct);
+
+    proc_macro::TokenStream::from(quote! {
+            #[derive(anchor_lang::__private::ZeroCopyAccessor, Copy, Clone)]
+            #[repr(packed)]
+            #account_strct
+    })
+}

lang/src/lib.rs

@@ -23,6 +23,7 @@
 
 extern crate self as anchor_lang;
 
+use bytemuck::{Pod, Zeroable};
 use solana_program::account_info::AccountInfo;
 use solana_program::instruction::AccountMeta;
 use solana_program::program_error::ProgramError;
@@ -38,28 +39,21 @@ mod ctor;
 mod error;
 #[doc(hidden)]
 pub mod idl;
+mod loader;
 mod program_account;
 mod state;
 mod sysvar;
 mod vec;
 
-// Internal module used by macros.
-#[doc(hidden)]
-pub mod __private {
-    pub use crate::ctor::Ctor;
-    pub use crate::error::Error;
-    pub use anchor_attribute_event::EventIndex;
-    pub use base64;
-}
-
 pub use crate::context::{Context, CpiContext, CpiStateContext};
 pub use crate::cpi_account::CpiAccount;
 pub use crate::cpi_state::CpiState;
+pub use crate::loader::Loader;
 pub use crate::program_account::ProgramAccount;
 pub use crate::state::ProgramState;
 pub use crate::sysvar::Sysvar;
 pub use anchor_attribute_access_control::access_control;
-pub use anchor_attribute_account::{account, associated};
+pub use anchor_attribute_account::{account, associated, zero_copy};
 pub use anchor_attribute_error::error;
 pub use anchor_attribute_event::{emit, event};
 pub use anchor_attribute_interface::interface;
@@ -172,6 +166,9 @@ pub trait AccountDeserialize: Sized {
     fn try_deserialize_unchecked(buf: &mut &[u8]) -> Result<Self, ProgramError>;
 }
 
+/// An account data structure capable of zero copy deserialization.
+pub trait ZeroCopy: Discriminator + Copy + Clone + Zeroable + Pod {}
+
 /// Calculates the data for an instruction invocation, where the data is
 /// `Sha256(<namespace>::<method_name>)[..8] || BorshSerialize(args)`.
 /// `args` is a borsh serialized struct of named fields for each argument given
@@ -215,10 +212,10 @@ pub trait Bump {
 pub mod prelude {
     pub use super::{
         access_control, account, associated, emit, error, event, interface, program, state,
-        AccountDeserialize, AccountSerialize, Accounts, AccountsExit, AccountsInit,
+        zero_copy, AccountDeserialize, AccountSerialize, Accounts, AccountsExit, AccountsInit,
         AnchorDeserialize, AnchorSerialize, Context, CpiAccount, CpiContext, CpiState,
-        CpiStateContext, ProgramAccount, ProgramState, Sysvar, ToAccountInfo, ToAccountInfos,
-        ToAccountMetas,
+        CpiStateContext, Loader, ProgramAccount, ProgramState, Sysvar, ToAccountInfo,
+        ToAccountInfos, ToAccountMetas,
     };
 
     pub use borsh;
@@ -241,3 +238,31 @@ pub mod prelude {
     pub use solana_program::sysvar::Sysvar as SolanaSysvar;
     pub use thiserror;
 }
+
+// Internal module used by macros.
+#[doc(hidden)]
+pub mod __private {
+    use solana_program::pubkey::Pubkey;
+
+    pub use crate::ctor::Ctor;
+    pub use crate::error::Error;
+    pub use anchor_attribute_account::ZeroCopyAccessor;
+    pub use anchor_attribute_event::EventIndex;
+    pub use base64;
+    pub use bytemuck;
+
+    // Very experimental trait.
+    pub trait ZeroCopyAccessor<Ty> {
+        fn get(&self) -> Ty;
+        fn set(input: &Ty) -> Self;
+    }
+
+    impl ZeroCopyAccessor<Pubkey> for [u8; 32] {
+        fn get(&self) -> Pubkey {
+            Pubkey::new(self)
+        }
+        fn set(input: &Pubkey) -> [u8; 32] {
+            input.to_bytes()
+        }
+    }
+}

lang/src/loader.rs

@@ -0,0 +1,198 @@
+use crate::{
+    Accounts, AccountsExit, AccountsInit, ToAccountInfo, ToAccountInfos, ToAccountMetas, ZeroCopy,
+};
+use solana_program::account_info::AccountInfo;
+use solana_program::entrypoint::ProgramResult;
+use solana_program::instruction::AccountMeta;
+use solana_program::program_error::ProgramError;
+use solana_program::pubkey::Pubkey;
+use std::cell::{Ref, RefMut};
+use std::io::Write;
+use std::marker::PhantomData;
+use std::ops::DerefMut;
+
+/// Account loader facilitating on demand zero copy deserialization.
+/// Note that using accounts in this way is distinctly different from using,
+/// for example, the [`ProgramAccount`](./struct.ProgramAccount.html). Namely,
+/// one must call `load`, `load_mut`, or `load_init`, before reading or writing
+/// to the account. For more details on zero-copy-deserialization, see the
+/// [`account`](./attr.account.html) attribute.
+///
+/// When using it's important to be mindful of any calls to `load` so as not to
+/// induce a `RefCell` panic, especially when sharing accounts across CPI
+/// boundaries. When in doubt, one should make sure all refs resulting from a
+/// call to `load` are dropped before CPI.
+pub struct Loader<'info, T: ZeroCopy> {
+    acc_info: AccountInfo<'info>,
+    phantom: PhantomData<&'info T>,
+}
+
+impl<'info, T: ZeroCopy> Loader<'info, T> {
+    fn new(acc_info: AccountInfo<'info>) -> Loader<'info, T> {
+        Self {
+            acc_info,
+            phantom: PhantomData,
+        }
+    }
+
+    /// Constructs a new `Loader` from a previously initialized account.
+    #[inline(never)]
+    pub fn try_from(acc_info: &AccountInfo<'info>) -> Result<Loader<'info, T>, ProgramError> {
+        let data: &[u8] = &acc_info.try_borrow_data()?;
+
+        // Discriminator must match.
+        let mut disc_bytes = [0u8; 8];
+        disc_bytes.copy_from_slice(&data[..8]);
+        if disc_bytes != T::discriminator() {
+            return Err(ProgramError::InvalidAccountData);
+        }
+
+        Ok(Loader::new(acc_info.clone()))
+    }
+
+    /// Constructs a new `Loader` from an uninitialized account.
+    #[inline(never)]
+    pub fn try_from_init(acc_info: &AccountInfo<'info>) -> Result<Loader<'info, T>, ProgramError> {
+        let data = acc_info.try_borrow_data()?;
+
+        // The discriminator should be zero, since we're initializing.
+        let mut disc_bytes = [0u8; 8];
+        disc_bytes.copy_from_slice(&data[..8]);
+        let discriminator = u64::from_le_bytes(disc_bytes);
+        if discriminator != 0 {
+            return Err(ProgramError::InvalidAccountData);
+        }
+
+        Ok(Loader::new(acc_info.clone()))
+    }
+
+    /// Returns a Ref to the account data structure for reading.
+    pub fn load(&self) -> Result<Ref<T>, ProgramError> {
+        let data = self.acc_info.try_borrow_data()?;
+
+        let mut disc_bytes = [0u8; 8];
+        disc_bytes.copy_from_slice(&data[..8]);
+        if disc_bytes != T::discriminator() {
+            return Err(ProgramError::InvalidAccountData);
+        }
+
+        Ok(Ref::map(data, |data| bytemuck::from_bytes(&data[8..])))
+    }
+
+    /// Returns a `RefMut` to the account data structure for reading or writing.
+    pub fn load_mut(&self) -> Result<RefMut<T>, ProgramError> {
+        // AccountInfo api allows you to borrow mut even if the account isn't
+        // writable, so add this check for a better dev experience.
+        if !self.acc_info.is_writable {
+            return Err(ProgramError::Custom(87)); // todo: proper error
+        }
+
+        let data = self.acc_info.try_borrow_mut_data()?;
+
+        let mut disc_bytes = [0u8; 8];
+        disc_bytes.copy_from_slice(&data[..8]);
+        if disc_bytes != T::discriminator() {
+            return Err(ProgramError::InvalidAccountData);
+        }
+
+        Ok(RefMut::map(data, |data| {
+            bytemuck::from_bytes_mut(&mut data.deref_mut()[8..])
+        }))
+    }
+
+    /// Returns a `RefMut` to the account data structure for reading or writing.
+    /// Should only be called once, when the account is being initialized.
+    pub fn load_init(&self) -> Result<RefMut<T>, ProgramError> {
+        // AccountInfo api allows you to borrow mut even if the account isn't
+        // writable, so add this check for a better dev experience.
+        if !self.acc_info.is_writable {
+            return Err(ProgramError::Custom(87)); // todo: proper error
+        }
+
+        let data = self.acc_info.try_borrow_mut_data()?;
+
+        // The discriminator should be zero, since we're initializing.
+        let mut disc_bytes = [0u8; 8];
+        disc_bytes.copy_from_slice(&data[..8]);
+        let discriminator = u64::from_le_bytes(disc_bytes);
+        if discriminator != 0 {
+            return Err(ProgramError::InvalidAccountData);
+        }
+
+        Ok(RefMut::map(data, |data| {
+            bytemuck::from_bytes_mut(&mut data.deref_mut()[8..])
+        }))
+    }
+}
+
+impl<'info, T: ZeroCopy> Accounts<'info> for Loader<'info, T> {
+    #[inline(never)]
+    fn try_accounts(
+        program_id: &Pubkey,
+        accounts: &mut &[AccountInfo<'info>],
+    ) -> Result<Self, ProgramError> {
+        if accounts.is_empty() {
+            return Err(ProgramError::NotEnoughAccountKeys);
+        }
+        let account = &accounts[0];
+        *accounts = &accounts[1..];
+        let l = Loader::try_from(account)?;
+        if l.acc_info.owner != program_id {
+            return Err(ProgramError::Custom(1)); // todo: proper error
+        }
+        Ok(l)
+    }
+}
+
+impl<'info, T: ZeroCopy> AccountsInit<'info> for Loader<'info, T> {
+    #[inline(never)]
+    fn try_accounts_init(
+        program_id: &Pubkey,
+        accounts: &mut &[AccountInfo<'info>],
+    ) -> Result<Self, ProgramError> {
+        if accounts.is_empty() {
+            return Err(ProgramError::NotEnoughAccountKeys);
+        }
+        let account = &accounts[0];
+        *accounts = &accounts[1..];
+        let l = Loader::try_from_init(account)?;
+        if l.acc_info.owner != program_id {
+            return Err(ProgramError::Custom(1)); // todo: proper error
+        }
+        Ok(l)
+    }
+}
+
+impl<'info, T: ZeroCopy> AccountsExit<'info> for Loader<'info, T> {
+    // The account *cannot* be loaded when this is called.
+    fn exit(&self, _program_id: &Pubkey) -> ProgramResult {
+        let mut data = self.acc_info.try_borrow_mut_data()?;
+        let dst: &mut [u8] = &mut data;
+        let mut cursor = std::io::Cursor::new(dst);
+        cursor.write_all(&T::discriminator()).unwrap();
+        Ok(())
+    }
+}
+
+impl<'info, T: ZeroCopy> ToAccountMetas for Loader<'info, T> {
+    fn to_account_metas(&self, is_signer: Option<bool>) -> Vec<AccountMeta> {
+        let is_signer = is_signer.unwrap_or(self.acc_info.is_signer);
+        let meta = match self.acc_info.is_writable {
+            false => AccountMeta::new_readonly(*self.acc_info.key, is_signer),
+            true => AccountMeta::new(*self.acc_info.key, is_signer),
+        };
+        vec![meta]
+    }
+}
+
+impl<'info, T: ZeroCopy> ToAccountInfos<'info> for Loader<'info, T> {
+    fn to_account_infos(&self) -> Vec<AccountInfo<'info>> {
+        vec![self.acc_info.clone()]
+    }
+}
+
+impl<'info, T: ZeroCopy> ToAccountInfo<'info> for Loader<'info, T> {
+    fn to_account_info(&self) -> AccountInfo<'info> {
+        self.acc_info.clone()
+    }
+}

lang/src/program_account.rs

@@ -90,7 +90,7 @@ where
 {
     #[inline(never)]
     fn try_accounts_init(
-        _program_id: &Pubkey,
+        program_id: &Pubkey,
         accounts: &mut &[AccountInfo<'info>],
     ) -> Result<Self, ProgramError> {
         if accounts.is_empty() {
@@ -98,7 +98,11 @@ where
         }
         let account = &accounts[0];
         *accounts = &accounts[1..];
-        ProgramAccount::try_from_init(account)
+        let pa = ProgramAccount::try_from_init(account)?;
+        if pa.inner.info.owner != program_id {
+            return Err(ProgramError::Custom(1)); // todo: proper error
+        }
+        Ok(pa)
     }
 }
 

lang/syn/src/codegen/accounts.rs

@@ -399,8 +399,12 @@ pub fn generate_constraint_belongs_to(
 ) -> proc_macro2::TokenStream {
     let target = c.join_target.clone();
     let ident = &f.ident;
+    let field = match &f.ty {
+        Ty::Loader(_) => quote! {#ident.load()?},
+        _ => quote! {#ident},
+    };
     quote! {
-        if &#ident.#target != #target.to_account_info().key {
+        if &#field.#target != #target.to_account_info().key {
             return Err(anchor_lang::solana_program::program_error::ProgramError::Custom(1)); // todo: error codes
         }
     }
@@ -454,6 +458,7 @@ pub fn generate_constraint_rent_exempt(
     let info = match f.ty {
         Ty::AccountInfo => quote! { #ident },
         Ty::ProgramAccount(_) => quote! { #ident.to_account_info() },
+        Ty::Loader(_) => quote! { #ident.to_account_info() },
         _ => panic!("Invalid syntax: rent exemption cannot be specified."),
     };
     match c {
@@ -497,7 +502,7 @@ pub fn generate_constraint_state(f: &Field, c: &ConstraintState) -> proc_macro2:
     let ident = &f.ident;
     let account_ty = match &f.ty {
         Ty::CpiState(ty) => &ty.account_ident,
-        _ => panic!("Invalid syntax"),
+        _ => panic!("Invalid state constraint"),
     };
     quote! {
         // Checks the given state account is the canonical state account for
@@ -517,15 +522,28 @@ pub fn generate_constraint_associated(
 ) -> proc_macro2::TokenStream {
     let associated_target = c.associated_target.clone();
     let field = &f.ident;
-    let account_ty = match &f.ty {
-        Ty::ProgramAccount(ty) => &ty.account_ident,
-        _ => panic!("Invalid syntax"),
+    let (account_ty, is_zero_copy) = match &f.ty {
+        Ty::ProgramAccount(ty) => (&ty.account_ident, false),
+        Ty::Loader(ty) => (&ty.account_ident, true),
+        _ => panic!("Invalid associated constraint"),
     };
 
     let space = match &f.space {
-        None => quote! {
-            let space = 8 + #account_ty::default().try_to_vec().unwrap().len();
+        // If no explicit space param was given, serialize the type to bytes
+        // and take the length (with +8 for the discriminator.)
+        None => match is_zero_copy {
+            false => {
+                quote! {
+                    let space = 8 + #account_ty::default().try_to_vec().unwrap().len();
+                }
+            }
+            true => {
+                quote! {
+                    let space = 8 + anchor_lang::__private::bytemuck::bytes_of(&#account_ty::default()).len();
+                }
+            }
         },
+        // Explicit account size given. Use it.
         Some(s) => quote! {
             let space = #s;
         },
@@ -579,8 +597,24 @@ pub fn generate_constraint_associated(
         }
     };
 
+    let account_wrapper_ty = match is_zero_copy {
+        false => quote! {
+            anchor_lang::ProgramAccount
+        },
+        true => quote! {
+            anchor_lang::Loader
+        },
+    };
+    let nonce_assignment = match is_zero_copy {
+        false => quote! {},
+        // Zero copy is not deserialized, so the data must be lazy loaded.
+        true => quote! {
+            .load_init()?
+        },
+    };
+
     quote! {
-        let #field: anchor_lang::ProgramAccount<#account_ty> = {
+        let #field: #account_wrapper_ty<#account_ty> = {
             #space
             #payer
 
@@ -617,10 +651,10 @@ pub fn generate_constraint_associated(
             })?;
             // For now, we assume all accounts created with the `associated`
             // attribute have a `nonce` field in their account.
-            let mut pa: anchor_lang::ProgramAccount<#account_ty> = anchor_lang::ProgramAccount::try_from_init(
+            let mut pa: #account_wrapper_ty<#account_ty> = #account_wrapper_ty::try_from_init(
                 &#field,
             )?;
-            pa.__nonce = nonce;
+            pa#nonce_assignment.__nonce = nonce;
             pa
         };
     }

lang/syn/src/idl.rs

@@ -128,6 +128,7 @@ pub enum IdlType {
     Defined(String),
     Option(Box<IdlType>),
     Vec(Box<IdlType>),
+    Array(Box<IdlType>, usize),
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
@@ -140,7 +141,6 @@ impl std::str::FromStr for IdlType {
         // Eliminate whitespace.
         let mut s = s.to_string();
         s.retain(|c| !c.is_whitespace());
-
         let r = match s.as_str() {
             "bool" => IdlType::Bool,
             "u8" => IdlType::U8,
@@ -158,7 +158,17 @@ impl std::str::FromStr for IdlType {
             "Pubkey" => IdlType::PublicKey,
             _ => match s.to_string().strip_prefix("Option<") {
                 None => match s.to_string().strip_prefix("Vec<") {
-                    None => IdlType::Defined(s.to_string()),
+                    None => match s.to_string().strip_prefix("[") {
+                        None => IdlType::Defined(s.to_string()),
+                        Some(inner) => {
+                            let inner = &inner[..inner.len() - 1];
+                            let mut parts = inner.split(";");
+                            let ty = IdlType::from_str(parts.next().unwrap()).unwrap();
+                            let len = parts.next().unwrap().parse::<usize>().unwrap();
+                            assert!(parts.next().is_none());
+                            IdlType::Array(Box::new(ty), len)
+                        }
+                    },
                     Some(inner) => {
                         let inner_ty = Self::from_str(
                             inner

lang/syn/src/lib.rs

@@ -204,6 +204,12 @@ impl Field {
                     ProgramAccount<#account>
                 }
             }
+            Ty::Loader(ty) => {
+                let account = &ty.account_ident;
+                quote! {
+                    Loader<#account>
+                }
+            }
             Ty::CpiAccount(ty) => {
                 let account = &ty.account_ident;
                 quote! {
@@ -242,6 +248,7 @@ pub enum Ty {
     ProgramState(ProgramStateTy),
     CpiState(CpiStateTy),
     ProgramAccount(ProgramAccountTy),
+    Loader(LoaderTy),
     CpiAccount(CpiAccountTy),
     Sysvar(SysvarTy),
 }
@@ -282,6 +289,12 @@ pub struct CpiAccountTy {
     pub account_ident: syn::Ident,
 }
 
+#[derive(Debug, PartialEq)]
+pub struct LoaderTy {
+    // The struct type of the account.
+    pub account_ident: syn::Ident,
+}
+
 // An access control constraint for an account.
 #[derive(Debug)]
 pub enum Constraint {

lang/syn/src/parser/accounts.rs

@@ -2,7 +2,7 @@ use crate::{
     AccountField, AccountsStruct, CompositeField, Constraint, ConstraintAssociated,
     ConstraintBelongsTo, ConstraintExecutable, ConstraintLiteral, ConstraintOwner,
     ConstraintRentExempt, ConstraintSeeds, ConstraintSigner, ConstraintState, CpiAccountTy,
-    CpiStateTy, Field, ProgramAccountTy, ProgramStateTy, SysvarTy, Ty,
+    CpiStateTy, Field, LoaderTy, ProgramAccountTy, ProgramStateTy, SysvarTy, Ty,
 };
 
 pub fn parse(strct: &syn::ItemStruct) -> AccountsStruct {
@@ -72,7 +72,7 @@ fn parse_field(f: &syn::Field, anchor: Option<&syn::Attribute>) -> AccountField
 fn is_field_primitive(f: &syn::Field) -> bool {
     match ident_string(f).as_str() {
         "ProgramState" | "ProgramAccount" | "CpiAccount" | "Sysvar" | "AccountInfo"
-        | "CpiState" => true,
+        | "CpiState" | "Loader" => true,
         _ => false,
     }
 }
@@ -89,6 +89,7 @@ fn parse_ty(f: &syn::Field) -> Ty {
         "CpiAccount" => Ty::CpiAccount(parse_cpi_account(&path)),
         "Sysvar" => Ty::Sysvar(parse_sysvar(&path)),
         "AccountInfo" => Ty::AccountInfo,
+        "Loader" => Ty::Loader(parse_program_account_zero_copy(&path)),
         _ => panic!("invalid account type"),
     }
 }
@@ -124,6 +125,11 @@ fn parse_program_account(path: &syn::Path) -> ProgramAccountTy {
     ProgramAccountTy { account_ident }
 }
 
+fn parse_program_account_zero_copy(path: &syn::Path) -> LoaderTy {
+    let account_ident = parse_account(path);
+    LoaderTy { account_ident }
+}
+
 fn parse_account(path: &syn::Path) -> syn::Ident {
     let segments = &path.segments[0];
     match &segments.arguments {

ts/package.json

@@ -20,7 +20,7 @@
     "prepublishOnly": "yarn build"
   },
   "dependencies": {
-    "@project-serum/borsh": "^0.1.0",
+    "@project-serum/borsh": "^0.1.1",
     "@solana/web3.js": "^1.2.0",
     "@types/bn.js": "^4.11.6",
     "@types/bs58": "^4.0.1",

ts/src/coder.ts

@@ -1,6 +1,6 @@
 import camelCase from "camelcase";
 import { snakeCase } from "snake-case";
-import { Layout } from "buffer-layout";
+import { Layout, seq } from "buffer-layout";
 import * as sha256 from "js-sha256";
 import * as borsh from "@project-serum/borsh";
 import {
@@ -349,6 +349,20 @@ class IdlCoder {
             throw new IdlError(`Type not found: ${JSON.stringify(field)}`);
           }
           return IdlCoder.typeDefLayout(filtered[0], types, fieldName);
+          // @ts-ignore
+        } else if (field.type.array) {
+          // @ts-ignore
+          let arrayTy = field.type.array[0];
+          // @ts-ignore
+          let arrayLen = field.type.array[1];
+          let innerLayout = IdlCoder.fieldLayout(
+            {
+              name: undefined,
+              type: arrayTy,
+            },
+            types
+          );
+          return borsh.array(innerLayout, arrayLen, fieldName);
         } else {
           throw new Error(`Not yet implemented: ${field}`);
         }
@@ -464,6 +478,15 @@ function typeSize(idl: Idl, ty: IdlType): number {
 
         return accountSize(idl, typeDef);
       }
+      // @ts-ignore
+      if (ty.array !== undefined) {
+        // @ts-ignore
+        let arrayTy = ty.array[0];
+        // @ts-ignore
+        let arraySize = ty.array[1];
+        // @ts-ignore
+        return typeSize(idl, arrayTy) * arraySize;
+      }
       throw new Error(`Invalid type ${JSON.stringify(ty)}`);
   }
 }

ts/yarn.lock

@@ -654,10 +654,10 @@
     "@nodelib/fs.scandir" "2.1.4"
     fastq "^1.6.0"
 
-"@project-serum/borsh@^0.1.0":
-  version "0.1.0"
-  resolved "https://registry.yarnpkg.com/@project-serum/borsh/-/borsh-0.1.0.tgz#cdbff90d06901f8206afb6e1998e5c45aae0aea7"
-  integrity sha512-AWZ/cjThXmb7o2/fMocc8/VaEsqH29yXEwdHnzTXzglxg1vLPZXpBHqGuPfonSfbd7WszgnGXAIHc+9artwMGg==
+"@project-serum/borsh@^0.1.1":
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/@project-serum/borsh/-/borsh-0.1.1.tgz#a810aad74e4b458fbd1ab63188f175bee765a8af"
+  integrity sha512-bzCea8KTyc7CNkcMn0V2HW/FdU9pnJUcVRrwLqvJkYeo+mhkXE4AxxWErN3q+UxhEm8ypGIX1OYTKJaTJvj5cQ==
   dependencies:
     bn.js "^5.1.2"
     buffer-layout "^1.2.0"