From 028e1a631629c7f5959e522dee80188ea7534d8f Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Sat, 27 Mar 2021 15:50:39 -0600
Subject: refactor makefile elements into submodules

---
 src/makefile/target.rs | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 src/makefile/target.rs

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

diff --git a/src/makefile/target.rs b/src/makefile/target.rs
new file mode 100644
index 0000000..1fbc75b
--- /dev/null
+++ b/src/makefile/target.rs
@@ -0,0 +1,77 @@
+use std::cell::Cell;
+use std::fmt;
+use std::fs::metadata;
+use std::time::SystemTime;
+
+use crate::makefile::command_line::CommandLine;
+
+use super::Makefile;
+
+#[derive(PartialEq, Eq, Clone, Debug)]
+pub struct Target {
+    pub name: String,
+    pub prerequisites: Vec<String>,
+    pub commands: Vec<CommandLine>,
+    pub already_updated: Cell<bool>,
+}
+
+impl Target {
+    fn modified_time(&self) -> Option<SystemTime> {
+        metadata(&self.name)
+            .and_then(|metadata| metadata.modified())
+            .ok()
+    }
+
+    pub fn newer_than(&self, other: &Target) -> Option<bool> {
+        let self_updated = self.already_updated.get();
+        let other_updated = other.already_updated.get();
+        Some(match (self.modified_time(), other.modified_time()) {
+            (Some(self_mtime), Some(other_mtime)) => self_mtime >= other_mtime,
+            // per POSIX: "If the target does not exist after the target has been
+            // successfully made up-to-date, the target shall be treated as being
+            // newer than any target for which it is a prerequisite."
+            (None, _) if self_updated && other.prerequisites.contains(&self.name) => true,
+            (_, None) if other_updated && self.prerequisites.contains(&other.name) => false,
+            _ => return None,
+        })
+    }
+
+    fn is_up_to_date(&self, file: &Makefile) -> bool {
+        if self.already_updated.get() {
+            return true;
+        }
+        let exists = metadata(&self.name).is_ok();
+        let newer_than_all_dependencies = self.prerequisites.iter().all(|t| {
+            self.newer_than(&file.get_target(t).borrow())
+                .unwrap_or(false)
+        });
+        exists && newer_than_all_dependencies
+    }
+
+    pub fn update(&self, file: &Makefile) {
+        for prereq in &self.prerequisites {
+            file.update_target(prereq);
+        }
+        if !self.is_up_to_date(file) {
+            self.execute_commands(file);
+        }
+        self.already_updated.set(true);
+    }
+
+    fn execute_commands(&self, file: &Makefile) {
+        for command in &self.commands {
+            command.execute(file, self);
+        }
+    }
+}
+
+impl fmt::Display for Target {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let prereqs = self.prerequisites.join(" ");
+        writeln!(f, "{}: {}", &self.name, prereqs)?;
+        for command in &self.commands {
+            writeln!(f, "\t{}", command)?;
+        }
+        Ok(())
+    }
+}
-- 
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