Migrate code into into stand-alone repo

Adds Cargo.toml files

.gitignore

@@ -0,0 +1,3 @@
+/target/
+**/*.rs.bk
+*.swp

Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "argh"
+version = "0.1.0"
+authors = ["Taylor Cramer <[email protected]>", "Benjamin Brittain<[email protected]>"]
+edition = "2018"
+license = "BSD License 2.0"
+description = "Derive-based argument parser optimized for code size"
+repository = "https://github.com/google/argh"
+
+[dependencies]
+argh_shared = {path = "./argh_shared"}
+argh_derive = {path = "./argh_derive"}

README.md

@@ -1,2 +1,4 @@
 # Argh
-**Argh is an opinionated Derive-based argument parsing optimized for code size**
+**Argh is an opinionated Derive-based argument parser optimized for code size**
+
+NOTE: This is not an officially supported Google product.

argh_derive/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "argh_derive"
+version = "0.1.0"
+authors = ["Taylor Cramer <[email protected]>", "Benjamin Brittain<[email protected]>"]
+edition = "2018"
+license = "BSD License 2.0"
+description = "Derive-based argument parsing optimized for code size"
+repository = "https://github.com/google/argh"
+
+[lib]
+proc-macro = true
+
+[dependencies]
+heck = "0.3.1"
+proc-macro2 = "1.0"
+quote = "1.0"
+syn = "1.0"
+argh_shared = {path = "../argh_shared" }

argh_derive/src/errors.rs

@@ -0,0 +1,161 @@
+// Copyright (c) 2020 Google LLC All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+use {
+    proc_macro2::{Span, TokenStream},
+    quote::ToTokens,
+    std::cell::RefCell,
+};
+
+/// A type for collecting procedural macro errors.
+#[derive(Default)]
+pub struct Errors {
+    errors: RefCell<Vec<syn::Error>>,
+}
+
+/// Produce functions to expect particular variants of `syn::Lit`
+macro_rules! expect_lit_fn {
+    ($(($fn_name:ident, $syn_type:ident, $variant:ident, $lit_name:literal),)*) => {
+        $(
+            pub fn $fn_name<'a>(&self, lit: &'a syn::Lit) -> Option<&'a syn::$syn_type> {
+                if let syn::Lit::$variant(inner) = lit {
+                    Some(inner)
+                } else {
+                    self.unexpected_lit($lit_name, lit);
+                    None
+                }
+            }
+        )*
+    }
+}
+
+/// Produce functions to expect particular variants of `syn::Meta`
+macro_rules! expect_meta_fn {
+    ($(($fn_name:ident, $syn_type:ident, $variant:ident, $meta_name:literal),)*) => {
+        $(
+            pub fn $fn_name<'a>(&self, meta: &'a syn::Meta) -> Option<&'a syn::$syn_type> {
+                if let syn::Meta::$variant(inner) = meta {
+                    Some(inner)
+                } else {
+                    self.unexpected_meta($meta_name, meta);
+                    None
+                }
+            }
+        )*
+    }
+}
+
+impl Errors {
+    /// Issue an error like:
+    ///
+    /// Duplicate foo attribute
+    /// First foo attribute here
+    pub fn duplicate_attrs(
+        &self,
+        attr_kind: &str,
+        first: &impl syn::spanned::Spanned,
+        second: &impl syn::spanned::Spanned,
+    ) {
+        self.duplicate_attrs_inner(attr_kind, first.span(), second.span())
+    }
+
+    fn duplicate_attrs_inner(&self, attr_kind: &str, first: Span, second: Span) {
+        self.err_span(second, &["Duplicate ", attr_kind, " attribute"].concat());
+        self.err_span(first, &["First ", attr_kind, " attribute here"].concat());
+    }
+
+    /// Error on literals, expecting attribute syntax.
+    pub fn expect_nested_meta<'a>(&self, nm: &'a syn::NestedMeta) -> Option<&'a syn::Meta> {
+        match nm {
+            syn::NestedMeta::Lit(l) => {
+                self.err(l, "Unexpected literal");
+                None
+            }
+            syn::NestedMeta::Meta(m) => Some(m),
+        }
+    }
+
+    /// Error on attribute syntax, expecting literals
+    pub fn expect_nested_lit<'a>(&self, nm: &'a syn::NestedMeta) -> Option<&'a syn::Lit> {
+        match nm {
+            syn::NestedMeta::Meta(m) => {
+                self.err(m, "Expected literal");
+                None
+            }
+            syn::NestedMeta::Lit(l) => Some(l),
+        }
+    }
+
+    expect_lit_fn![
+        (expect_lit_str, LitStr, Str, "string"),
+        (expect_lit_char, LitChar, Char, "character"),
+        (expect_lit_int, LitInt, Int, "integer"),
+    ];
+
+    expect_meta_fn![
+        (expect_meta_word, Path, Path, "path"),
+        (expect_meta_list, MetaList, List, "list"),
+        (expect_meta_name_value, MetaNameValue, NameValue, "name-value pair"),
+    ];
+
+    fn unexpected_lit(&self, expected: &str, found: &syn::Lit) {
+        fn lit_kind(lit: &syn::Lit) -> &'static str {
+            use syn::Lit::{Bool, Byte, ByteStr, Char, Float, Int, Str, Verbatim};
+            match lit {
+                Str(_) => "string",
+                ByteStr(_) => "bytestring",
+                Byte(_) => "byte",
+                Char(_) => "character",
+                Int(_) => "integer",
+                Float(_) => "float",
+                Bool(_) => "boolean",
+                Verbatim(_) => "unknown (possibly extra-large integer)",
+            }
+        }
+
+        self.err(
+            found,
+            &["Expected ", expected, " literal, found ", lit_kind(found), " literal"].concat(),
+        )
+    }
+
+    fn unexpected_meta(&self, expected: &str, found: &syn::Meta) {
+        fn meta_kind(meta: &syn::Meta) -> &'static str {
+            use syn::Meta::{List, NameValue, Path};
+            match meta {
+                Path(_) => "path",
+                List(_) => "list",
+                NameValue(_) => "name-value pair",
+            }
+        }
+
+        self.err(
+            found,
+            &["Expected ", expected, " attribute, found ", meta_kind(found), " attribute"].concat(),
+        )
+    }
+
+    /// Issue an error relating to a particular `Spanned` structure.
+    pub fn err(&self, spanned: &impl syn::spanned::Spanned, msg: &str) {
+        self.err_span(spanned.span(), msg);
+    }
+
+    /// Issue an error relating to a particular `Span`.
+    pub fn err_span(&self, span: Span, msg: &str) {
+        self.push(syn::Error::new(span, msg));
+    }
+
+    /// Push a `syn::Error` onto the list of errors to issue.
+    pub fn push(&self, err: syn::Error) {
+        self.errors.borrow_mut().push(err);
+    }
+}
+
+impl ToTokens for Errors {
+    /// Convert the errors into tokens that, when emit, will cause
+    /// the user of the macro to receive compiler errors.
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.extend(self.errors.borrow().iter().map(|e| e.to_compile_error()));
+    }
+}