implement `eval`

1 files changed, 20 insertions, 8 deletions

diff --git a/src/makefile/input.rs b/src/makefile/input.rs
index 918ce0a..f269fa4 100644
--- a/src/makefile/input.rs
+++ b/src/makefile/input.rs
@@ -2,7 +2,7 @@ use std::cell::Cell;
 use std::collections::HashMap;
 use std::error::Error as StdError;
 use std::fs::File;
-use std::io::{BufRead, BufReader, Error as IoError, Lines};
+use std::io::{BufRead, BufReader, Cursor, Error as IoError, Lines};
 use std::iter::Peekable;
 use std::path::Path;
 
@@ -181,7 +181,10 @@ impl<'a, R: BufRead> MakefileReader<'a, R> {
                 // POSIX says we only have to handle a single filename, but GNU make
                 // handles arbitrarily many filenames, and it's not like that's more work
                 for field in fields {
-                    self.extend(MakefileReader::read_file(self.args, field)?);
+                    self.extend(
+                        MakefileReader::read_file(self.args, field)
+                            .with_context(|| format!("while including {}", field))?,
+                    );
                 }
                 continue;
             }
@@ -202,7 +205,18 @@ impl<'a, R: BufRead> MakefileReader<'a, R> {
 
             // before we actually test it, see if it's only visible after expanding macros
             let (line_tokens, line_type) = if let LineType::Unknown = line_type {
-                let line_tokens = TokenString::text(self.expand_macros(&line_tokens)?);
+                let line_tokens = TokenString::text(self.expand_macros(&line_tokens)?.trim());
+                // and let's eval whatever bullshit needs evaling
+                #[cfg(feature = "full")]
+                {
+                    let eval = self.macros.to_eval.take();
+                    for eval in eval {
+                        self.extend(
+                            MakefileReader::read(self.args, Cursor::new(eval))
+                                .context("while evaling")?,
+                        );
+                    }
+                }
                 let line_type = LineType::of(&line_tokens);
                 (line_tokens, line_type)
             } else {
@@ -499,8 +513,6 @@ impl<'a, R: BufRead> MakefileReader<'a, R> {
 
 #[cfg(test)]
 mod test {
-    use std::io::Cursor;
-
     use super::*;
 
     type R = Result<()>;
@@ -545,7 +557,7 @@ endef
     }
 
     #[test]
-    #[ignore = "I still haven't implemented `eval` or %-based macro substitution."]
+    #[cfg(feature = "full")]
     fn eval() -> R {
         // This, for the record, is a terrible misfeature.
         // If you need this, you probably shouldn't be using Make.
@@ -574,10 +586,10 @@ endef
 $(foreach prog,$(PROGRAMS),$(eval $(call PROGRAM_template,$(prog))))
 
 $(PROGRAMS):
-        $(LINK.o) $^ $(LDLIBS) -o $@
+\t$(LINK.o) $^ $(LDLIBS) -o $@
 
 clean:
-        rm -f $(ALL_OBJS) $(PROGRAMS)
+\trm -f $(ALL_OBJS) $(PROGRAMS)
         ";
 
         let args = Args::empty();