From 40920ea9d255f704116064d0b831666c7416caf2 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Sun, 28 Mar 2021 00:36:23 -0600
Subject: add (& somewhat test!) GNUful conditionals

---
 src/makefile/mod.rs | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)

(limited to 'src/makefile/mod.rs')

diff --git a/src/makefile/mod.rs b/src/makefile/mod.rs
index 2f73c70..0d4cded 100644
--- a/src/makefile/mod.rs
+++ b/src/makefile/mod.rs
@@ -13,11 +13,13 @@ use regex::Regex;
 use crate::args::Args;
 
 mod command_line;
+mod conditional;
 mod inference_rules;
 mod target;
 mod token;
 
 use command_line::CommandLine;
+use conditional::{ConditionalLine, ConditionalState};
 use inference_rules::InferenceRule;
 use target::Target;
 use token::{tokenize, Token, TokenString};
@@ -151,6 +153,7 @@ impl<'a> Makefile<'a> {
 
     pub(crate) fn and_read(&mut self, source: impl BufRead) {
         let mut lines_iter = source.lines().enumerate().peekable();
+        let mut conditional_stack: Vec<ConditionalState> = vec![];
         while let Some((line_number, line)) = lines_iter.next() {
             // TODO handle I/O errors at all
             let mut line = line.expect("failed to read line of makefile!");
@@ -170,6 +173,14 @@ impl<'a> Makefile<'a> {
             }
             let line = COMMENT.replace(&line, "").into_owned();
 
+            // skip lines if we need to
+            if conditional_stack
+                .last()
+                .map_or(false, ConditionalState::skipping)
+            {
+                continue;
+            }
+
             // handle include lines
             if let Some(line) = line.strip_prefix("include ") {
                 // remove extra leading space
@@ -181,6 +192,14 @@ impl<'a> Makefile<'a> {
                 for field in fields {
                     self.and_read_file(field);
                 }
+            } else if let Some(line) = ConditionalLine::from(&line, |t| self.expand_macros(t, None))
+            {
+                line.action(
+                    conditional_stack.last(),
+                    |name| self.macros.contains_key(name),
+                    |t| self.expand_macros(t, None),
+                )
+                .apply_to(&mut conditional_stack);
             } else if line.trim().is_empty() {
                 // handle blank lines
                 continue;
@@ -728,3 +747,38 @@ fn builtin_targets() -> Vec<Target> {
         already_updated: Cell::new(false),
     }]
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    use std::io::Cursor;
+
+    fn empty_makefile(args: &Args) -> Makefile {
+        Makefile {
+            inference_rules: vec![],
+            macros: HashMap::new(),
+            targets: RefCell::new(HashMap::new()),
+            first_non_special_target: None,
+            args,
+        }
+    }
+
+    #[test]
+    fn basic_conditionals() {
+        let file = "
+ifeq (1,1)
+worked = yes
+else ifeq (2,2)
+worked = no
+endif
+        ";
+        let args = Args::empty();
+        let mut makefile = empty_makefile(&args);
+        makefile.and_read(Cursor::new(file));
+        assert_eq!(
+            makefile.expand_macros(&"$(worked)".parse().unwrap(), None),
+            "yes"
+        );
+    }
+}
-- 
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