build.rs: add proc-macro to generate Override structs for configuration

1 files changed, 185 insertions, 0 deletions

diff --git a/config_macros.rs b/config_macros.rs
new file mode 100644
index 00000000..7ce5a0ce
--- /dev/null
+++ b/config_macros.rs
@@ -0,0 +1,185 @@
+/*
+ * meli -
+ *
+ * Copyright  Manos Pitsidianakis
+ *
+ * This file is part of meli.
+ *
+ * meli is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * meli is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with meli. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+use std::fs::File;
+use std::io::prelude::*;
+use std::process::{Command, Stdio};
+
+use quote::{format_ident, quote};
+
+// Write ConfigStructOverride to overrides.rs
+pub fn override_derive(filenames: &[(&str, &str)]) {
+    let mut output_file =
+        File::create("src/conf/overrides.rs").expect("Unable to open output file");
+    let mut output_string = r##"/*
+ * meli - conf/overrides.rs
+ *
+ * Copyright 2020 Manos Pitsidianakis
+ *
+ * This file is part of meli.
+ *
+ * meli is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * meli is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with meli. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+//! This module is automatically generated by build.rs.
+use super::*;
+
+"##
+    .to_string();
+
+    'file_loop: for (filename, ident) in filenames {
+        println!("cargo:rerun-if-changed={}", filename);
+        let mut file = File::open(&filename).expect(&format!("Unable to open file `{}`", filename));
+
+        let mut src = String::new();
+        file.read_to_string(&mut src).expect("Unable to read file");
+
+        let syntax = syn::parse_file(&src).expect("Unable to parse file");
+        if syntax.items.iter().any(|item| {
+            if let syn::Item::Struct(s) = item {
+                if s.ident.to_string().ends_with("Override") {
+                    println!("ident {} exists, skipping {}", ident, filename);
+                    return true;
+                }
+            }
+            false
+        }) {
+            continue 'file_loop;
+        }
+
+        for item in syntax.items.iter() {
+            if let syn::Item::Struct(s) = item {
+                if s.ident != ident {
+                    continue;
+                }
+                if s.ident.to_string().ends_with("Override") {
+                    unreachable!();
+                }
+                let override_ident: syn::Ident = format_ident!("{}Override", s.ident);
+                let mut field_tokentrees = vec![];
+                let mut field_idents = vec![];
+                for f in &s.fields {
+                    let ident = &f.ident;
+                    let ty = &f.ty;
+                    let attrs = f
+                        .attrs
+                        .iter()
+                        .filter_map(|f| {
+                            let mut new_attr = f.clone();
+                            if let quote::__private::TokenTree::Group(g) =
+                                f.tokens.clone().into_iter().next().unwrap()
+                            {
+                                let attr_inner_value = f.tokens.to_string();
+                                if !attr_inner_value.starts_with("( default")
+                                    && !attr_inner_value.starts_with("( default =")
+                                {
+                                    return None;
+                                }
+                                if attr_inner_value.starts_with("( default =") {
+                                    let rest = g.stream().clone().into_iter().skip(4);
+                                    new_attr.tokens = quote! { ( #(#rest)*) };
+                                    if new_attr.tokens.to_string().as_str() == "( )" {
+                                        return None;
+                                    }
+                                } else if attr_inner_value.starts_with("( default") {
+                                    let rest = g.stream().clone().into_iter().skip(2);
+                                    new_attr.tokens = quote! { ( #(#rest)*) };
+                                    if new_attr.tokens.to_string().as_str() == "( )" {
+                                        return None;
+                                    }
+                                }
+                            }
+
+                            Some(new_attr)
+                        })
+                        .collect::<Vec<_>>();
+                    let t = quote! {
+                        #(#attrs)*
+                        #[serde(default)]
+                        pub #ident : Option<#ty>
+                    };
+                    field_idents.push(ident);
+                    field_tokentrees.push(t);
+                }
+                //let fields = &s.fields;
+
+                let literal_struct = quote! {
+                    #[derive(Debug, Serialize, Deserialize, Clone)]
+                    pub struct #override_ident {
+                        #(#field_tokentrees),*
+                    }
+
+
+                    impl Default for #override_ident {
+                        fn default() -> Self {
+                            #override_ident {
+                                #(#field_idents: None),*
+                            }
+                        }
+                    }
+                };
+                output_string.extend(literal_struct.to_string().chars());
+                output_string.push_str("\n\n");
+            }
+        }
+    }
+
+    /*
+    let mut rustfmt = Command::new("rustfmt")
+        .stdin(Stdio::piped())
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .spawn()
+        .expect("failed to execute rustfmt");
+
+    {
+        // limited borrow of stdin
+        let stdin = rustfmt
+            .stdin
+            .as_mut()
+            .expect("failed to get rustfmt stdin");
+        stdin
+            .write_all(output_string.as_bytes())
+            .expect("failed to write to rustfmit stdin");
+    }
+
+    let output = rustfmt
+        .wait_with_output()
+        .expect("failed to wait on rustfmt child");
+    if !output.stderr.is_empty() {
+        panic!(format!("{}", String::from_utf8_lossy(&output.stderr)));
+    }
+
+    output_file.write_all(&output.stdout).unwrap();
+    */
+    output_file.write_all(output_string.as_bytes()).unwrap();
+}