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rust: Refactor name handling
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@jakelang
jakelang committed May 9, 2019
1 parent 9fda06a commit de5cf2f
Showing 1 changed file with 88 additions and 51 deletions.
139 changes: 88 additions & 51 deletions bindings/rust/evmc-declare/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,67 @@ use syn::Meta;
use syn::MetaList;
use syn::NestedMeta;

struct VMNameSet {
type_name: String,
name_allcaps: String,
name_lowercase: String,
}

impl VMNameSet {
fn new(ident: String) -> Self {
let caps = ident.to_shouty_snake_case();
let lowercase = ident
.to_snake_case()
.chars()
.filter(|c| *c != '_')
.collect();
VMNameSet {
type_name: ident,
name_allcaps: caps,
name_lowercase: lowercase,
}
}

/// Return a reference to the struct name, as a string.
fn get_type_name(&self) -> &String {
&self.type_name
}

/// Return a reference to the name in shouty snake case.
fn get_name_caps(&self) -> &String {
&self.name_allcaps
}

/// Return a reference to the name in lowercase, with all underscores removed. (Used for
/// symbols like evmc_create_vmname)
fn get_name_lowercase(&self) -> &String {
&self.name_lowercase
}

/// Get the struct's name as an explicit identifier to be interpolated with quote.
fn get_type_as_ident(&self) -> Ident {
Ident::new(&self.type_name, self.type_name.span())
}

/// Get the lowercase name appended with arbitrary text as an explicit ident.
fn get_lowercase_as_ident_append(&self, suffix: &str) -> Ident {
let concat = format!("{}{}", &self.name_lowercase, suffix);
Ident::new(&concat, self.name_lowercase.span())
}

/// Get the lowercase name prepended with arbitrary text as an explicit ident.
fn get_lowercase_as_ident_prepend(&self, prefix: &str) -> Ident {
let concat = format!("{}{}", prefix, &self.name_lowercase);
Ident::new(&concat, self.name_lowercase.span())
}

/// Get the lowercase name appended with arbitrary text as an explicit ident.
fn get_caps_as_ident_append(&self, suffix: &str) -> Ident {
let concat = format!("{}{}", &self.name_allcaps, suffix);
Ident::new(&concat, self.name_allcaps.span())
}
}

#[proc_macro_attribute]
pub fn evmc_declare_vm(args: TokenStream, item: TokenStream) -> TokenStream {
// First, try to parse the input token stream into an AST node representing a struct
Expand All @@ -27,15 +88,8 @@ pub fn evmc_declare_vm(args: TokenStream, item: TokenStream) -> TokenStream {
// Extract the identifier of the struct from the AST node.
let vm_type_name: String = input.ident.to_string();

// Get the name in shouty snake case for the statically defined VM data.
let vm_name_allcaps: String = vm_type_name.to_shouty_snake_case();

// Get the name in snake case and strip the underscores for the symbol name.
let vm_name_lowercase: String = vm_type_name
.to_snake_case()
.chars()
.filter(|c| *c != '_')
.collect();
// Build the VM name set.
let names = VMNameSet::new(vm_type_name);

// Parse the attribute meta-items for the name and version. Verify param count.
let meta = parse_macro_input!(args as MetaList);
Expand Down Expand Up @@ -72,12 +126,11 @@ pub fn evmc_declare_vm(args: TokenStream, item: TokenStream) -> TokenStream {
let vm_version_string = env!("CARGO_PKG_VERSION").to_string();

// Get all the tokens from the respective helpers.
let static_data_tokens =
build_static_data(&vm_name_stylized, &vm_name_allcaps, &vm_version_string);
let capabilities_tokens = build_capabilities_fn(&vm_name_lowercase, vm_capabilities);
let create_tokens = build_create_fn(&vm_name_lowercase, &vm_name_allcaps, &vm_type_name);
let destroy_tokens = build_destroy_fn(&vm_name_lowercase, &vm_type_name);
let execute_tokens = build_execute_fn(&vm_name_lowercase, &vm_type_name);
let static_data_tokens = build_static_data(&names, &vm_name_stylized, &vm_version_string);
let capabilities_tokens = build_capabilities_fn(&names, vm_capabilities);
let create_tokens = build_create_fn(&names);
let destroy_tokens = build_destroy_fn(&names);
let execute_tokens = build_execute_fn(&names);

let quoted = quote! {
#input
Expand All @@ -91,10 +144,9 @@ pub fn evmc_declare_vm(args: TokenStream, item: TokenStream) -> TokenStream {
quoted.into()
}

fn build_execute_fn(name_lowercase: &String, type_name: &String) -> proc_macro2::TokenStream {
let fn_name_string = format!("{}_execute", name_lowercase);
let fn_name_ident = Ident::new(&fn_name_string, name_lowercase.span());
let type_name_ident = Ident::new(type_name, type_name.span());
fn build_execute_fn(names: &VMNameSet) -> proc_macro2::TokenStream {
let fn_name_ident = names.get_lowercase_as_ident_append("_execute");
let type_name_ident = names.get_type_as_ident();

quote! {
extern "C" fn #fn_name_ident(
Expand Down Expand Up @@ -132,26 +184,15 @@ fn build_execute_fn(name_lowercase: &String, type_name: &String) -> proc_macro2:
}

/// Takes an identifier and struct definition, builds an evmc_create_* function for FFI.
fn build_create_fn(
name_lowercase: &String,
name_caps: &String,
type_name: &String,
) -> proc_macro2::TokenStream {
let fn_name = format!("evmc_create_{}", name_lowercase);
let fn_ident = Ident::new(&fn_name, name_lowercase.span());
let type_ident = Ident::new(type_name, type_name.span());

// TODO: reduce code duplication here.
let capabilities_fn_string = format!("{}_get_capabilities", name_lowercase);
let capabilities_fn_ident = Ident::new(&capabilities_fn_string, name_lowercase.span());
let destroy_fn_string = format!("{}_destroy", name_lowercase);
let destroy_fn_ident = Ident::new(&destroy_fn_string, name_lowercase.span());
let static_name_string = format!("{}_NAME", name_caps);
let static_version_string = format!("{}_VERSION", name_caps);
let static_name_ident = Ident::new(&static_name_string, name_caps.span());
let static_version_ident = Ident::new(&static_version_string, name_caps.span());
let execute_fn_string = format!("{}_execute", name_lowercase);
let execute_fn_ident = Ident::new(&execute_fn_string, name_lowercase.span());
fn build_create_fn(names: &VMNameSet) -> proc_macro2::TokenStream {
let type_ident = names.get_type_as_ident();
let fn_ident = names.get_lowercase_as_ident_prepend("evmc_create_");

let execute_fn_ident = names.get_lowercase_as_ident_append("_execute");
let capabilities_fn_ident = names.get_lowercase_as_ident_append("_get_capabilities");
let destroy_fn_ident = names.get_lowercase_as_ident_append("_destroy");
let static_version_ident = names.get_caps_as_ident_append("_VERSION");
let static_name_ident = names.get_caps_as_ident_append("_NAME");

quote! {
#[no_mangle]
Expand All @@ -173,10 +214,9 @@ fn build_create_fn(
}

/// Builds a callback to dispose of the VM instance
fn build_destroy_fn(name_lowercase: &String, type_name: &String) -> proc_macro2::TokenStream {
let fn_ident_string = format!("{}_destroy", name_lowercase);
let fn_ident = Ident::new(&fn_ident_string, name_lowercase.span());
let type_ident = Ident::new(type_name, type_name.span());
fn build_destroy_fn(names: &VMNameSet) -> proc_macro2::TokenStream {
let type_ident = names.get_type_as_ident();
let fn_ident = names.get_lowercase_as_ident_append("_destroy");

quote! {
extern "C" fn #fn_ident(instance: *mut ::evmc_sys::evmc_instance) {
Expand All @@ -186,10 +226,9 @@ fn build_destroy_fn(name_lowercase: &String, type_name: &String) -> proc_macro2:
}

/// Takes a capabilities flag and builds the evmc_get_capabilities callback.
fn build_capabilities_fn(name_lowercase: &String, capabilities: u32) -> proc_macro2::TokenStream {
fn build_capabilities_fn(names: &VMNameSet, capabilities: u32) -> proc_macro2::TokenStream {
// Could avoid using a special name and just use get_capabilities.
let concatenated = format!("{}_get_capabilities", name_lowercase);
let capabilities_fn_ident = Ident::new(&concatenated, name_lowercase.span());
let capabilities_fn_ident = names.get_lowercase_as_ident_append("_get_capabilities");
let capabilities_literal =
LitInt::new(capabilities as u64, IntSuffix::U32, capabilities.span());

Expand All @@ -202,15 +241,13 @@ fn build_capabilities_fn(name_lowercase: &String, capabilities: u32) -> proc_mac

/// Generate tokens for the static data associated with an EVMC VM.
fn build_static_data(
names: &VMNameSet,
name_stylized: &String,
name_allcaps: &String,
version: &String,
) -> proc_macro2::TokenStream {
// Stitch together the VM name and the suffix _NAME
let concatenated_name = format!("{}_NAME", name_allcaps);
let concatenated_version = format!("{}_VERSION", name_allcaps);
let static_name_ident = Ident::new(&concatenated_name, name_allcaps.span());
let static_version_ident = Ident::new(&concatenated_version, name_allcaps.span());
let static_name_ident = names.get_lowercase_as_ident_append("_NAME");
let static_version_ident = names.get_lowercase_as_ident_append("_VERSION");

// Turn the stylized VM name and version into string literals.
// FIXME: Not sure if the span of name.as_str() is the same as that of name.
Expand Down

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