Add a 'FromFormValue' derive. Start 'codegen_next' crate.

The 'codegen_next' crate will eventually be renamed 'codegen'. It
contains procedural macros written with the upcoming 'proc_macro' APIs,
which will eventually be stabilized. All compiler extensions in the
present 'codegen' crate will be rewritten as procedural macros and moved
to the 'codegen_next' crate.

At present, macros from 'codegen_next' are exported from the core
`rocket` crate automatically. In the future, we may wish to feature-gate
this export to allow using Rocket's core without codegen.

Resolves #16.

Cargo.toml

@@ -5,6 +5,7 @@ codegen-units = 4
 members = [
   "lib/",
   "codegen/",
+  "codegen_next/",
   "contrib/",
   "examples/cookies",
   "examples/errors",

README.md

@@ -13,7 +13,7 @@ expressibility, and speed. Here's an example of a complete Rocket application:
 #![feature(plugin, decl_macro)]
 #![plugin(rocket_codegen)]
 
-extern crate rocket;
+#[macro_use] extern crate rocket;
 
 #[get("/<name>/<age>")]
 fn hello(name: String, age: u8) -> String {

codegen_next/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "rocket_codegen_next"
+version = "0.4.0-dev"
+authors = ["Sergio Benitez <sb@sergio.bz>"]
+description = "Procedural macros for the Rocket web framework."
+documentation = "https://api.rocket.rs/rocket_codegen/"
+homepage = "https://rocket.rs"
+repository = "https://github.com/SergioBenitez/Rocket"
+readme = "../README.md"
+keywords = ["rocket", "web", "framework", "code", "generation"]
+license = "MIT/Apache-2.0"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+quote = "0.5.1"
+proc-macro2 = { version = "0.3.6", features = ["nightly"] }
+syn = { version = "0.13.1", features = ["full", "extra-traits"] }

codegen_next/src/codegen_ext.rs

@@ -0,0 +1,101 @@
+use syn::*;
+use ext::*;
+use quote::Tokens;
+use spanned::Spanned;
+
+use FieldMember;
+
+pub trait CodegenFieldsExt {
+    fn surround(&self, tokens: Tokens) -> Tokens;
+    fn ignore_tokens(&self) -> Tokens;
+    fn id_match_tokens(&self) -> Tokens;
+}
+
+pub fn field_to_ident(i: usize, field: &Field) -> Ident {
+    let name = match field.ident {
+        Some(id) => format!("_{}", id),
+        None => format!("_{}", i)
+    };
+
+    Ident::new(&name, field.span().into())
+}
+
+pub fn field_to_match((i, field): (usize, &Field)) -> Tokens {
+    let ident = field_to_ident(i, field);
+    match field.ident {
+        Some(id) => quote!(#id: #ident),
+        None => quote!(#ident)
+    }
+}
+
+impl CodegenFieldsExt for Fields {
+    fn surround(&self, tokens: Tokens) -> Tokens {
+        match *self {
+            Fields::Named(..) => quote!({ #tokens }),
+            Fields::Unnamed(..) => quote!(( #tokens )),
+            Fields::Unit => quote!()
+        }
+    }
+
+    fn ignore_tokens(&self) -> Tokens {
+        self.surround(quote!(..))
+    }
+
+    fn id_match_tokens(&self) -> Tokens {
+        let idents = self.iter()
+            .enumerate()
+            .map(field_to_match);
+
+        self.surround(quote!(#(#idents),*))
+    }
+}
+
+pub trait TokensExt {
+    fn tokens(&self) -> Tokens;
+}
+
+impl<'f> TokensExt for FieldMember<'f> {
+    fn tokens(&self) -> Tokens {
+        let index = self.member.unnamed().map(|i| i.index).unwrap_or(0);
+        let ident = field_to_ident(index as usize, &self.field);
+        quote!(#ident)
+    }
+}
+
+// use rocket::http::{ContentType, MediaType, Status};
+
+// impl TokensExt for ContentType {
+//     fn tokens(&self) -> Tokens {
+//         let mt_tokens = self.0.tokens();
+//         quote!(rocket::http::ContentType(#mt_tokens))
+//     }
+// }
+
+// impl TokensExt for MediaType {
+//     fn tokens(&self) -> Tokens {
+//         let (top, sub) = (self.top().as_str(), self.sub().as_str());
+//         let (keys, values) = (self.params().map(|(k, _)| k), self.params().map(|(_, v)| v));
+//         quote!(rocket::http::MediaType {
+//             source: rocket::http::Source::None,
+//             top: rocket::http::IndexedStr::Concrete(
+//                 std::borrow::Cow::Borrowed(#top)
+//             ),
+//             sub: rocket::http::IndexedStr::Concrete(
+//                 std::borrow::Cow::Borrowed(#sub)
+//             ),
+//             params: rocket::http::MediaParams::Static(&[
+//                 #((
+//                     rocket::http::IndexedStr::Concrete(std::borrow::Cow::Borrowed(#keys)),
+//                     rocket::http::IndexedStr::Concrete(std::borrow::Cow::Borrowed(#values))
+//                 )),*
+//             ])
+//         })
+//     }
+// }
+
+// impl TokensExt for Status {
+//     fn tokens(&self) -> Tokens {
+//         let (code, reason) = (self.code, self.reason);
+//         quote!(rocket::http::Status { code: #code, reason: #reason })
+//     }
+// }

codegen_next/src/ext.rs

@@ -0,0 +1,169 @@
+use syn::*;
+use FieldMember;
+use spanned::Spanned;
+
+pub trait MemberExt {
+    fn named(&self) -> Option<&Ident>;
+    fn unnamed(&self) -> Option<&Index>;
+}
+
+impl MemberExt for Member {
+    fn named(&self) -> Option<&Ident> {
+        match *self {
+            Member::Named(ref named) => Some(named),
+            _ => None
+        }
+    }
+
+    fn unnamed(&self) -> Option<&Index> {
+        match *self {
+            Member::Unnamed(ref unnamed) => Some(unnamed),
+            _ => None
+        }
+    }
+}
+
+pub(crate) trait FieldsExt {
+    fn len(&self) -> usize;
+    fn is_empty(&self) -> bool;
+    fn named(&self) -> Option<&FieldsNamed>;
+    fn is_named(&self) -> bool;
+    fn unnamed(&self) -> Option<&FieldsUnnamed>;
+    fn is_unnamed(&self) -> bool;
+    fn is_unit(&self) -> bool;
+    fn nth(&self, i: usize) -> Option<&Field>;
+    fn find_member(&self, member: &Member) -> Option<&Field>;
+    fn to_field_members<'f>(&'f self) -> Box<Iterator<Item = FieldMember<'f>> + 'f>;
+}
+
+impl FieldsExt for Fields {
+    fn len(&self) -> usize {
+        match *self {
+            Fields::Named(ref fields) => fields.named.len(),
+            Fields::Unnamed(ref fields) => fields.unnamed.len(),
+            Fields::Unit => 0
+        }
+    }
+
+    fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+
+    fn named(&self) -> Option<&FieldsNamed> {
+        match *self {
+            Fields::Named(ref named) => Some(named),
+            _ => None
+        }
+    }
+
+    fn is_named(&self) -> bool {
+        self.named().is_some()
+    }
+
+    fn unnamed(&self) -> Option<&FieldsUnnamed> {
+        match *self {
+            Fields::Unnamed(ref unnamed) => Some(unnamed),
+            _ => None
+        }
+    }
+
+    fn is_unnamed(&self) -> bool {
+        self.unnamed().is_some()
+    }
+
+    fn is_unit(&self) -> bool {
+        match *self {
+            Fields::Unit => true,
+            _ => false
+        }
+    }
+
+    fn to_field_members<'f>(&'f self) -> Box<Iterator<Item = FieldMember<'f>> + 'f> {
+        Box::new(self.iter().enumerate().map(|(index, field)| {
+            if let Some(ident) = field.ident {
+                FieldMember { field, member: Member::Named(ident) }
+            } else {
+                let index = Index { index: index as u32, span: field.span().into() };
+                let member = Member::Unnamed(index);
+                FieldMember { field, member }
+            }
+        }))
+    }
+
+    fn nth(&self, i: usize) -> Option<&Field> {
+        match *self {
+            Fields::Named(ref fields) => fields.named.iter().nth(i),
+            Fields::Unnamed(ref fields) => fields.unnamed.iter().nth(i),
+            Fields::Unit => None
+        }
+    }
+
+    fn find_member(&self, member: &Member) -> Option<&Field> {
+        if let (Some(fields), Some(ident)) = (self.named(), member.named()) {
+            fields.named.iter().find(|f| f.ident.as_ref().unwrap() == ident)
+        } else if let (Some(fields), Some(member)) = (self.unnamed(), member.unnamed()) {
+            fields.unnamed.iter().nth(member.index as usize)
+        } else {
+            None
+        }
+    }
+}
+
+pub trait PathExt {
+    fn is(&self, global: bool, segments: &[&str]) -> bool;
+    fn is_local(&self, segments: &[&str]) -> bool;
+    fn is_global(&self, segments: &[&str]) -> bool;
+}
+
+impl PathExt for Path {
+    fn is(&self, global: bool, segments: &[&str]) -> bool {
+        if self.global() != global || self.segments.len() != segments.len() {
+            return false;
+        }
+
+        for (segment, wanted) in self.segments.iter().zip(segments.iter()) {
+            if segment.ident != wanted {
+                return false;
+            }
+        }
+
+        true
+    }
+
+    fn is_local(&self, segments: &[&str]) -> bool {
+        self.is(false, segments)
+    }
+
+    fn is_global(&self, segments: &[&str]) -> bool {
+        self.is(true, segments)
+    }
+}
+
+pub trait DataExt {
+    fn into_enum(self) -> Option<DataEnum>;
+    fn into_struct(self) -> Option<DataStruct>;
+    fn into_union(self) -> Option<DataUnion>;
+}
+
+impl DataExt for Data {
+    fn into_enum(self) -> Option<DataEnum> {
+        match self {
+            Data::Enum(e) => Some(e),
+            _ => None
+        }
+    }
+
+    fn into_struct(self) -> Option<DataStruct> {
+        match self {
+            Data::Struct(s) => Some(s),
+            _ => None
+        }
+    }
+
+    fn into_union(self) -> Option<DataUnion> {
+        match self {
+            Data::Union(u) => Some(u),
+            _ => None
+        }
+    }
+}

codegen_next/src/lib.rs

@@ -0,0 +1,103 @@
+#![feature(proc_macro, core_intrinsics, decl_macro)]
+#![recursion_limit="256"]
+
+extern crate syn;
+extern crate proc_macro;
+extern crate proc_macro2;
+#[macro_use] extern crate quote;
+
+mod parser;
+mod spanned;
+mod ext;
+mod codegen_ext;
+
+use parser::Result as PResult;
+use proc_macro::{Span, TokenStream};
+use spanned::Spanned;
+
+use ext::*;
+use syn::*;
+
+const NO_FIELDS_ERR: &str = "variants in `FromFormValue` derives cannot have fields";
+const NO_GENERICS: &str = "enums with generics cannot derive `FromFormValue`";
+const ONLY_ENUMS: &str = "`FromFormValue` can only be derived for enums";
+const EMPTY_ENUM_WARN: &str = "deriving `FromFormValue` for empty enum";
+
+#[derive(Debug, Clone)]
+pub(crate) struct FieldMember<'f> {
+    field: &'f Field,
+    member: Member
+}
+
+fn validate_input(input: DeriveInput) -> PResult<DataEnum> {
+    // This derive doesn't support generics. Error out if there are generics.
+    if !input.generics.params.is_empty() {
+        return Err(input.generics.span().error(NO_GENERICS));
+    }
+
+    // This derive only works for enums. Error out if the input is not an enum.
+    let input_span = input.span();
+    let data = input.data.into_enum().ok_or_else(|| input_span.error(ONLY_ENUMS))?;
+
+    // This derive only works for variants that are nullary.
+    for variant in data.variants.iter() {
+        if !variant.fields.is_empty() {
+            return Err(variant.span().error(NO_FIELDS_ERR));
+        }
+    }
+
+    // Emit a warning if the enum is empty.
+    if data.variants.is_empty() {
+        Span::call_site().warning(EMPTY_ENUM_WARN).emit();
+    }
+
+    Ok(data)
+}
+
+fn real_derive_from_form_value(input: TokenStream) -> PResult<TokenStream> {
+    // Parse the input `TokenStream` as a `syn::DeriveInput`, an AST.
+    let input: DeriveInput = syn::parse(input).map_err(|e| {
+        Span::call_site().error(format!("error: failed to parse input: {:?}", e))
+    })?;
+
+    // Validate the enum.
+    let name = input.ident;
+    let enum_data = validate_input(input)?;
+
+    // Create iterators over the identifers as idents and as strings.
+    let variant_strs = enum_data.variants.iter().map(|v| v.ident.as_ref() as &str);
+    let variant_idents = enum_data.variants.iter().map(|v| v.ident);
+    let names = ::std::iter::repeat(name);
+
+    // Generate the implementation.
+    Ok(quote! {
+        mod scope {
+            extern crate std;
+            extern crate rocket;
+
+            use self::std::prelude::v1::*;
+            use self::rocket::request::FromFormValue;
+            use self::rocket::http::RawStr;
+
+            impl<'v> FromFormValue<'v> for #name {
+                type Error = &'v RawStr;
+
+                fn from_form_value(v: &'v RawStr) -> Result<Self, Self::Error> {
+                    #(if v.as_uncased_str() == #variant_strs {
+                        return Ok(#names::#variant_idents);
+                    })*
+
+                    Err(v)
+                }
+            }
+        }
+    }.into())
+}
+
+#[proc_macro_derive(FromFormValue)]
+pub fn derive_from_form_value(input: TokenStream) -> TokenStream {
+    real_derive_from_form_value(input).unwrap_or_else(|diag| {
+        diag.emit();
+        TokenStream::empty()
+    })
+}

codegen_next/src/parser.rs

@@ -0,0 +1,118 @@
+#![allow(dead_code)]
+
+use syn::token;
+use syn::synom::Synom;
+use syn::buffer::{Cursor, TokenBuffer};
+
+use proc_macro::{TokenStream, Span, Diagnostic};
+
+pub use proc_macro2::Delimiter;
+
+pub type Result<T> = ::std::result::Result<T, Diagnostic>;
+
+pub enum Seperator {
+    Comma,
+    Pipe,
+    Semi,
+}
+
+pub struct Parser {
+    buffer: Box<TokenBuffer>,
+    cursor: Cursor<'static>,
+}
+
+impl Parser {
+    pub fn new(tokens: TokenStream) -> Parser {
+        let buffer = Box::new(TokenBuffer::new(tokens.into()));
+        let cursor = unsafe {
+            let buffer: &'static TokenBuffer = ::std::mem::transmute(&*buffer);
+            buffer.begin()
+        };
+
+        Parser {
+            buffer: buffer,
+            cursor: cursor,
+        }
+    }
+
+    pub fn current_span(&self) -> Span {
+        self.cursor.token_tree()
+            .map(|_| self.cursor.span().unstable())
+            .unwrap_or_else(|| Span::call_site())
+    }
+
+    pub fn parse<T: Synom>(&mut self) -> Result<T> {
+        let (val, cursor) = T::parse(self.cursor)
+            .map_err(|e| {
+                let expected = match T::description() {
+                    Some(desc) => desc,
+                    None => unsafe { ::std::intrinsics::type_name::<T>() }
+                };
+
+                self.current_span().error(format!("{}: expected {}", e, expected))
+            })?;
+
+        self.cursor = cursor;
+        Ok(val)
+    }
+
+    pub fn eat<T: Synom>(&mut self) -> bool {
+        self.parse::<T>().is_ok()
+    }
+
+    pub fn parse_group<F, T>(&mut self, delim: Delimiter, f: F) -> Result<T>
+        where F: FnOnce(&mut Parser) -> Result<T>
+    {
+        if let Some((group_cursor, _, next_cursor)) = self.cursor.group(delim) {
+            self.cursor = group_cursor;
+            let result = f(self);
+            self.cursor = next_cursor;
+            result
+        } else {
+            let expected = match delim {
+                Delimiter::Brace => "curly braced group",
+                Delimiter::Bracket => "square bracketed group",
+                Delimiter::Parenthesis => "parenthesized group",
+                Delimiter::None => "invisible group"
+            };
+
+            Err(self.current_span()
+                .error(format!("parse error: expected {}", expected)))
+        }
+    }
+
+    pub fn parse_sep<F, T>(&mut self, sep: Seperator, mut f: F) -> Result<Vec<T>>
+        where F: FnMut(&mut Parser) -> Result<T>
+    {
+        let mut output = vec![];
+        while !self.is_eof() {
+            output.push(f(self)?);
+            let have_sep = match sep {
+                Seperator::Comma => self.eat::<token::Comma>(),
+                Seperator::Pipe => self.eat::<token::Or>(),
+                Seperator::Semi => self.eat::<token::Semi>(),
+            };
+
+            if !have_sep {
+                break;
+            }
+        }
+
+        Ok(output)
+    }
+
+    pub fn eof(&self) -> Result<()> {
+        if !self.cursor.eof() {
+            let diag = self.current_span()
+                .error("trailing characters; expected eof");
+
+            return Err(diag);
+        }
+
+        Ok(())
+    }
+
+    fn is_eof(&self) -> bool {
+        self.eof().is_ok()
+    }
+}

codegen_next/src/spanned.rs

@@ -0,0 +1,32 @@
+use proc_macro::Span;
+
+use proc_macro2::TokenStream;
+use quote::{Tokens, ToTokens};
+
+pub trait Spanned {
+    fn span(&self) -> Span;
+}
+
+// FIXME: Remove this once proc_macro's stabilize.
+impl<T: ToTokens> Spanned for T {
+    fn span(&self) -> Span {
+        let mut tokens = Tokens::new();
+        self.to_tokens(&mut tokens);
+        let token_stream = TokenStream::from(tokens);
+        let mut iter = token_stream.into_iter();
+        let mut span = match iter.next() {
+            Some(tt) => tt.span().unstable(),
+            None => {
+                return Span::call_site();
+            }
+        };
+
+        for tt in iter {
+            if let Some(joined) = span.join(tt.span().unstable()) {
+                span = joined;
+            }
+        }
+
+        span
+    }
+}

examples/form_kitchen_sink/src/main.rs

@@ -1,37 +1,22 @@
 #![feature(plugin, decl_macro, custom_derive)]
 #![plugin(rocket_codegen)]
 
-extern crate rocket;
+#[macro_use] extern crate rocket;
 
 use std::io;
 
-use rocket::request::{Form, FromFormValue};
+use rocket::request::Form;
 use rocket::response::NamedFile;
 use rocket::http::RawStr;
 
 #[cfg(test)] mod tests;
 
 // TODO: Make deriving `FromForm` for this enum possible.
-#[derive(Debug)]
+#[derive(Debug, FromFormValue)]
 enum FormOption {
     A, B, C
 }
 
-impl<'v> FromFormValue<'v> for FormOption {
-    type Error = &'v RawStr;
-
-    fn from_form_value(v: &'v RawStr) -> Result<Self, Self::Error> {
-        let variant = match v.as_str() {
-            "a" => FormOption::A,
-            "b" => FormOption::B,
-            "c" => FormOption::C,
-            _ => return Err(v)
-        };
-
-        Ok(variant)
-    }
-}
-
 #[derive(Debug, FromForm)]
 struct FormInput<'r> {
     checkbox: bool,

examples/form_kitchen_sink/src/tests.rs

@@ -131,9 +131,9 @@ fn check_semantically_invalid_forms() {
     form_vals[1] = "NaN";
     assert_invalid_form(&client, &mut form_vals);
 
-    form_vals[2] = "A";
+    form_vals[2] = "A?";
     assert_invalid_form(&client, &mut form_vals);
-    form_vals[2] = "B";
+    form_vals[2] = " B";
     assert_invalid_form(&client, &mut form_vals);
     form_vals[2] = "d";
     assert_invalid_form(&client, &mut form_vals);
@@ -143,7 +143,7 @@ fn check_semantically_invalid_forms() {
     assert_invalid_form(&client, &mut form_vals);
 
     // password and textarea are always valid, so we skip them
-    form_vals[5] = "A";
+    form_vals[5] = "A.";
     assert_invalid_form(&client, &mut form_vals);
     form_vals[5] = "b ";
     assert_invalid_form(&client, &mut form_vals);

lib/Cargo.toml

@@ -18,6 +18,7 @@ categories = ["web-programming::http-server"]
 tls = ["rustls", "hyper-sync-rustls"]
 
 [dependencies]
+rocket_codegen_next = { version = "0.4.0-dev", path = "../codegen_next" }
 yansi = "0.4"
 log = "0.4"
 percent-encoding = "1"
@@ -32,10 +33,14 @@ pear = { git = "http://github.com/SergioBenitez/pear" }
 pear_codegen = "0.0"
 rustls = { version = "0.12.0", optional = true }
 hyper = { version = "0.10.13", default-features = false }
-hyper-sync-rustls = { version = "=0.3.0-rc.2", features = ["server"], optional = true }
 indexmap = "1.0"
 isatty = "0.1"
 
+[dependencies.hyper-sync-rustls]
+version = "=0.3.0-rc.2"
+features = ["server"]
+optional = true
+
 [dependencies.cookie]
 git = "https://github.com/alexcrichton/cookie-rs"
 rev = "8579b4b"

lib/src/lib.rs

@@ -96,6 +96,9 @@
 //! module documentation](/rocket/local) and the [testing chapter of the
 //! guide](https://rocket.rs/guide/testing/#testing) include detailed examples.
 
+#[allow(unused_imports)] #[macro_use] extern crate rocket_codegen_next;
+#[doc(hidden)] pub use rocket_codegen_next::*;
+
 #[macro_use] extern crate log;
 #[macro_use] extern crate pear;
 #[cfg(feature = "tls")] extern crate rustls;