1 files changed, 189 insertions, 0 deletions
diff --git a/src/args.rs b/src/args.rs
new file mode 100644
index 0000000..1fe6731
--- /dev/null
+++ b/src/args.rs
@@ -0,0 +1,189 @@
+use std::env;
+use std::ffi::OsString;
+use std::path::PathBuf;
+
+use structopt::StructOpt;
+
+#[derive(StructOpt, Debug, PartialEq, Eq)]
+#[structopt(author, about)]
+pub struct Args {
+    /// Cause environment variables, including those with null values, to override macro
+    /// assignments within makefiles.
+    #[structopt(short, long)]
+    environment_overrides: bool,
+
+    /// Specify a different makefile (or '-' for standard input).
+    ///
+    /// The argument makefile is a pathname of a description file, which is also referred
+    /// to as the makefile. A pathname of '-' shall denote the standard input. There can
+    /// be multiple instances of this option, and they shall be processed in the order
+    /// specified. The effect of specifying the same option-argument more than once is
+    /// unspecified.
+    #[structopt(short = "f", long = "file", visible_alias = "makefile", number_of_values = 1, parse(from_os_str))]
+    makefile: Vec<PathBuf>,
+
+    /// Ignore error codes returned by invoked commands.
+    ///
+    /// This mode is the same as if the special target .IGNORE were specified without
+    /// prerequisites.
+    #[structopt(short, long)]
+    ignore_errors: bool,
+
+    /// Continue to update other targets that do not depend on the current target if a
+    /// non-ignored error occurs while executing the commands to bring a target
+    /// up-to-date.
+    #[structopt(short, long)]
+    keep_going: bool,
+
+    /// Write commands that would be executed on standard output, but do not execute them
+    /// (but execute lines starting with '+').
+    ///
+    /// However, lines with a <plus-sign> ( '+' ) prefix shall be executed. In this mode,
+    /// lines with an at-sign ( '@' ) character prefix shall be written to standard
+    /// output.
+    #[structopt(short = "n", long, visible_alias = "just-print", visible_alias = "recon")]
+    dry_run: bool,
+
+    /// Write to standard output the complete set of macro definitions and target
+    /// descriptions.
+    ///
+    /// The output format is unspecified.
+    #[structopt(short, long, visible_alias = "print-data-base")]
+    print_everything: bool,
+
+    /// Return a zero exit value if the target file is up-to-date; otherwise, return an
+    /// exit value of 1.
+    ///
+    /// Targets shall not be updated if this option is specified. However, a makefile
+    /// command line (associated with the targets) with a <plus-sign> ( '+' ) prefix
+    /// shall be executed.
+    #[structopt(short, long)]
+    question: bool,
+
+    /// Clear the suffix list and do not use the built-in rules.
+    #[structopt(short = "r", long)]
+    no_builtin_rules: bool,
+
+    /// Terminate make if an error occurs while executing the commands to bring a target
+    /// up-to-date (default behavior, required by POSIX to be also a flag for some
+    /// reason).
+    ///
+    /// This shall be the default and the opposite of -k.
+    #[structopt(short = "S", long, visible_alias = "stop", hidden = true, overrides_with="keep-going")]
+    no_keep_going: bool,
+
+    /// Do not write makefile command lines or touch messages to standard output before
+    /// executing.
+    ///
+    /// This mode shall be the same as if the special target .SILENT were specified
+    /// without prerequisites.
+    #[structopt(short, long, visible_alias = "quiet")]
+    silent: bool,
+
+    /// Update the modification time of each target as though a touch target had been
+    /// executed.
+    ///
+    /// Targets that have prerequisites but no commands, or that are already up-to-date,
+    /// shall not be touched in this manner. Write messages to standard output for each
+    /// target file indicating the name of the file and that it was touched. Normally,
+    /// the makefile command lines associated with each target are not executed. However,
+    /// a command line with a <plus-sign> ( '+' ) prefix shall be executed.
+    #[structopt(short, long)]
+    touch: bool,
+
+    /// Target names or macro definitions.
+    ///
+    /// If no target is specified, while make is processing the makefiles, the first
+    /// target that make encounters that is not a special target or an inference rule
+    /// shall be used.
+    targets_or_macros: Vec<String>,
+}
+
+impl Args {
+    pub fn from_env_and_args() -> Args {
+        // POSIX spec says "Any options specified in the MAKEFLAGS environment variable
+        // shall be evaluated before any options specified on the make utility command
+        // line."
+        // TODO make sure only flags show up in MAKEFLAGS (i.e. not -f or other stuff)
+        // TODO accept "option letters without the leading <hyphen-minus> characters"
+        let env_makeflags = env::var("MAKEFLAGS").unwrap_or_default();
+        let env_makeflags = env_makeflags.split_whitespace()
+            .map(|x| OsString::from(x));
+        let mut args = env::args_os();
+        // per the structopt docs, the first argument will be used as the binary name,
+        // so we need to make sure it goes in before MAKEFLAGS
+        let arg0 = args.next().unwrap_or_else(|| env!("CARGO_PKG_NAME").into());
+
+        let args = ::std::iter::once(arg0)
+            .chain(env_makeflags.into_iter())
+            .chain(args);
+        Args::from_iter(args)
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn no_args() {
+        let args: Vec<OsString> = vec!["makers".into()];
+        let args = Args::from_iter(args.into_iter());
+        assert_eq!(args, Args {
+            environment_overrides: false,
+            makefile: vec![],
+            ignore_errors: false,
+            keep_going: false,
+            dry_run: false,
+            print_everything: false,
+            question: false,
+            no_builtin_rules: false,
+            no_keep_going: false,
+            silent: false,
+            touch: false,
+            targets_or_macros: vec![],
+        });
+    }
+
+    #[test]
+    fn kitchen_sink_args() {
+        let args = "makers -eiknpqrstf foo -f bruh bar baz=yeet";
+        let args = Args::from_iter(args.split_whitespace());
+        assert_eq!(args, Args {
+            environment_overrides: true,
+            makefile: vec!["foo".into(), "bruh".into()],
+            ignore_errors: true,
+            keep_going: true,
+            dry_run: true,
+            print_everything: true,
+            question: true,
+            no_builtin_rules: true,
+            no_keep_going: false,
+            silent: true,
+            touch: true,
+            targets_or_macros: vec!["bar".into(), "baz=yeet".into()],
+        });
+    }
+
+    #[test]
+    fn keep_going_wrestling() {
+        let args = "makers -kSkSkSSSkSkkSk -k -S -k -k -S -S -k";
+        let args = Args::from_iter(args.split_whitespace());
+        assert_eq!(args, Args {
+            environment_overrides: false,
+            makefile: vec![],
+            ignore_errors: false,
+            keep_going: true,
+            dry_run: false,
+            print_everything: false,
+            question: false,
+            no_builtin_rules: false,
+            no_keep_going: false,
+            silent: false,
+            touch: false,
+            targets_or_macros: vec![],
+        });
+    }
+
+    // TODO test MAKEFLAGS
+}