src/tools/expand-yaml-anchors/src/main.rs

   1 use std::error::Error;
   2 use std::path::{Path, PathBuf};
   3 use yaml_rust::{Yaml, YamlEmitter, YamlLoader};
   4
   5 /// List of directories containing files to expand. The first tuple element is the source
   6 /// directory, while the second tuple element is the destination directory.
   7 #[rustfmt::skip]
   8 static TO_EXPAND: &[(&str, &str)] = &[
   9     ("src/ci/github-actions", ".github/workflows"),
  10 ];
  11
  12 /// Name of a special key that will be removed from all the maps in expanded configuration files.
  13 /// This key can then be used to contain shared anchors.
  14 static REMOVE_MAP_KEY: &str = "x--expand-yaml-anchors--remove";
  15
  16 /// Message that will be included at the top of all the expanded files. {source} will be replaced
  17 /// with the source filename relative to the base path.
  18 static HEADER_MESSAGE: &str = "\
  19 #############################################################
  20 #   WARNING: automatically generated file, DO NOT CHANGE!   #
  21 #############################################################
  22
  23 # This file was automatically generated by the expand-yaml-anchors tool. The
  24 # source file that generated this one is:
  25 #
  26 #   {source}
  27 #
  28 # Once you make changes to that file you need to run:
  29 #
  30 #   ./x.py run src/tools/expand-yaml-anchors/
  31 #
  32 # The CI build will fail if the tool is not run after changes to this file.
  33
  34 ";
  35
  36 enum Mode {
  37     Check,
  38     Generate,
  39 }
  40
  41 struct App {
  42     mode: Mode,
  43     base: PathBuf,
  44 }
  45
  46 impl App {
  47     fn from_args() -> Result<Self, Box<dyn Error>> {
  48         // Parse CLI arguments
  49         let args = std::env::args().skip(1).collect::<Vec<_>>();
  50         let (mode, base) = match args.iter().map(|s| s.as_str()).collect::<Vec<_>>().as_slice() {
  51             &["generate", ref base] => (Mode::Generate, PathBuf::from(base)),
  52             &["check", ref base] => (Mode::Check, PathBuf::from(base)),
  53             _ => {
  54                 eprintln!("usage: expand-yaml-anchors <source-dir> <dest-dir>");
  55                 std::process::exit(1);
  56             }
  57         };
  58
  59         Ok(App { mode, base })
  60     }
  61
  62     fn run(&self) -> Result<(), Box<dyn Error>> {
  63         for (source, dest) in TO_EXPAND {
  64             let source = self.base.join(source);
  65             let dest = self.base.join(dest);
  66             for entry in std::fs::read_dir(&source)? {
  67                 let path = entry?.path();
  68                 if !path.is_file() || path.extension().and_then(|e| e.to_str()) != Some("yml") {
  69                     continue;
  70                 }
  71
  72                 let dest_path = dest.join(path.file_name().unwrap());
  73                 self.expand(&path, &dest_path).with_context(|| match self.mode {
  74                     Mode::Generate => format!(
  75                         "failed to expand {} into {}",
  76                         self.path(&path),
  77                         self.path(&dest_path)
  78                     ),
  79                     Mode::Check => format!("{} is not up to date", self.path(&dest_path)),
  80                 })?;
  81             }
  82         }
  83         Ok(())
  84     }
  85
  86     fn expand(&self, source: &Path, dest: &Path) -> Result<(), Box<dyn Error>> {
  87         let content = std::fs::read_to_string(source)
  88             .with_context(|| format!("failed to read {}", self.path(source)))?;
  89
  90         let mut buf = HEADER_MESSAGE.replace("{source}", &self.path(source).to_string());
  91
  92         let documents = YamlLoader::load_from_str(&content)
  93             .with_context(|| format!("failed to parse {}", self.path(source)))?;
  94         for mut document in documents.into_iter() {
  95             document = yaml_merge_keys::merge_keys(document)
  96                 .with_context(|| format!("failed to expand {}", self.path(source)))?;
  97             document = filter_document(document);
  98
  99             YamlEmitter::new(&mut buf).dump(&document).map_err(|err| WithContext {
 100                 context: "failed to serialize the expanded yaml".into(),
 101                 source: Box::new(err),
 102             })?;
 103             buf.push('\n');
 104         }
 105
 106         match self.mode {
 107             Mode::Check => {
 108                 let old = std::fs::read_to_string(dest)
 109                     .with_context(|| format!("failed to read {}", self.path(dest)))?;
 110                 if old != buf {
 111                     return Err(Box::new(StrError(format!(
 112                         "{} and {} are different",
 113                         self.path(source),
 114                         self.path(dest),
 115                     ))));
 116                 }
 117             }
 118             Mode::Generate => {
 119                 std::fs::write(dest, buf.as_bytes())
 120                     .with_context(|| format!("failed to write to {}", self.path(dest)))?;
 121             }
 122         }
 123         Ok(())
 124     }
 125
 126     fn path<'a>(&self, path: &'a Path) -> impl std::fmt::Display + 'a {
 127         path.strip_prefix(&self.base).unwrap_or(path).display()
 128     }
 129 }
 130
 131 fn filter_document(document: Yaml) -> Yaml {
 132     match document {
 133         Yaml::Hash(map) => Yaml::Hash(
 134             map.into_iter()
 135                 .filter(|(key, _)| {
 136                     if let Yaml::String(string) = &key { string != REMOVE_MAP_KEY } else { true }
 137                 })
 138                 .map(|(key, value)| (filter_document(key), filter_document(value)))
 139                 .collect(),
 140         ),
 141         Yaml::Array(vec) => {
 142             Yaml::Array(vec.into_iter().map(|item| filter_document(item)).collect())
 143         }
 144         other => other,
 145     }
 146 }
 147
 148 fn main() {
 149     if let Err(err) = App::from_args().and_then(|app| app.run()) {
 150         eprintln!("error: {}", err);
 151
 152         let mut source = err.as_ref() as &dyn Error;
 153         while let Some(err) = source.source() {
 154             eprintln!("caused by: {}", err);
 155             source = err;
 156         }
 157
 158         std::process::exit(1);
 159     }
 160 }
 161
 162 #[derive(Debug)]
 163 struct StrError(String);
 164
 165 impl Error for StrError {}
 166
 167 impl std::fmt::Display for StrError {
 168     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
 169         std::fmt::Display::fmt(&self.0, f)
 170     }
 171 }
 172
 173 #[derive(Debug)]
 174 struct WithContext {
 175     context: String,
 176     source: Box<dyn Error>,
 177 }
 178
 179 impl std::fmt::Display for WithContext {
 180     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
 181         write!(f, "{}", self.context)
 182     }
 183 }
 184
 185 impl Error for WithContext {
 186     fn source(&self) -> Option<&(dyn Error + 'static)> {
 187         Some(self.source.as_ref())
 188     }
 189 }
 190
 191 pub(crate) trait ResultExt<T> {
 192     fn with_context<F: FnOnce() -> String>(self, f: F) -> Result<T, Box<dyn Error>>;
 193 }
 194
 195 impl<T, E: Into<Box<dyn Error>>> ResultExt<T> for Result<T, E> {
 196     fn with_context<F: FnOnce() -> String>(self, f: F) -> Result<T, Box<dyn Error>> {
 197         match self {
 198             Ok(ok) => Ok(ok),
 199             Err(err) => Err(WithContext { source: err.into(), context: f() }.into()),
 200         }
 201     }
 202 }