lay down boilerplate for function calls

of all the obnoxious GNUisms, this will probably wind up being the largest.
especially if huge makefiles (e.g. Linux) use most of the functions that GNU offers, meaning we have to implement most of them to be Linuxable

3 files changed, 98 insertions, 33 deletions

diff --git a/src/makefile/functions.rs b/src/makefile/functions.rs
new file mode 100644
index 0000000..bc39886
--- /dev/null
+++ b/src/makefile/functions.rs
@@ -0,0 +1,31 @@
+use super::token::TokenString;
+
+pub(crate) fn call(name: &str, args: &[TokenString]) -> TokenString {
+    match name {
+        // Text Functions
+        "filter" => todo!(),
+        "filter-out" => todo!(),
+        "sort" => todo!(),
+
+        // File Name Functions
+        "notdir" => todo!(),
+        "basename" => todo!(),
+        "addprefix" => todo!(),
+        "wildcard" => todo!(),
+
+        // foreach
+        "foreach" => todo!(),
+
+        // call
+        "call" => todo!(),
+
+        // eval
+        "eval" => todo!(),
+
+        // shell
+        "shell" => todo!(),
+
+        // fallback
+        _ => panic!("function not implemented: {}", name),
+    }
+}
diff --git a/src/makefile/mod.rs b/src/makefile/mod.rs
index 0d4cded..1fc8303 100644
--- a/src/makefile/mod.rs
+++ b/src/makefile/mod.rs
@@ -14,6 +14,7 @@ use crate::args::Args;
 
 mod command_line;
 mod conditional;
+mod functions;
 mod inference_rules;
 mod target;
 mod token;
@@ -592,6 +593,9 @@ impl<'a> Makefile<'a> {
                     };
                     result.push_str(&macro_value);
                 }
+                Token::FunctionCall { name, args } => {
+                    result.push_str(&self.expand_macros(&functions::call(name, args), None));
+                }
             }
         }
         result
diff --git a/src/makefile/token.rs b/src/makefile/token.rs
index 86c442b..eca40ed 100644
--- a/src/makefile/token.rs
+++ b/src/makefile/token.rs
@@ -4,9 +4,9 @@ use std::str::FromStr;
 use nom::{
     branch::alt,
     bytes::complete::{tag, take_till1, take_while1},
-    character::complete::anychar,
+    character::complete::{anychar, space1},
     combinator::{all_consuming, map, opt, verify},
-    multi::many1,
+    multi::{many1, separated_list1},
     sequence::{delimited, pair, preceded, separated_pair},
     Finish, IResult,
 };
@@ -110,6 +110,10 @@ pub(crate) enum Token {
         name: String,
         replacement: Option<(TokenString, TokenString)>,
     },
+    FunctionCall {
+        name: String,
+        args: Vec<TokenString>,
+    },
 }
 
 impl fmt::Display for Token {
@@ -124,34 +128,71 @@ impl fmt::Display for Token {
                 name,
                 replacement: Some((r1, r2)),
             } => write!(f, "$({}:{}={})", name, r1, r2),
+            Self::FunctionCall { name, args } => write!(
+                f,
+                "$({} {})",
+                name,
+                args.iter()
+                    .map(|x| format!("{}", x))
+                    .collect::<Vec<_>>()
+                    .join(", ")
+            ),
         }
     }
 }
 
-fn macro_name(input: &str) -> IResult<&str, &str> {
+fn macro_function_name(input: &str) -> IResult<&str, &str> {
     // POSIX says "periods, underscores, digits, and alphabetics from the portable character set"
-    take_while1(|c: char| c == '.' || c == '_' || c.is_alphanumeric())(input)
+    // one GNUism is a function with a - in the name
+    take_while1(|c: char| c == '.' || c == '_' || c.is_alphanumeric() || c == '-')(input)
 }
 
-fn macro_expansion_body<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
+fn macro_expansion_body<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> + 'a {
     let subst = preceded(
         tag(":"),
-        separated_pair(tokens_but_not('='), tag("="), tokens_but_not(end)),
+        separated_pair(
+            tokens_but_not(vec!['=']),
+            tag("="),
+            tokens_but_not(vec![end]),
+        ),
     );
-    map(pair(macro_name, opt(subst)), |(name, replacement)| {
-        Token::MacroExpansion {
+    map(
+        pair(macro_function_name, opt(subst)),
+        |(name, replacement)| Token::MacroExpansion {
             name: name.into(),
             replacement,
-        }
-    })
+        },
+    )
+}
+
+fn function_call_body<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
+    map(
+        separated_pair(
+            macro_function_name,
+            space1,
+            separated_list1(tag(","), tokens_but_not(vec![',', end])),
+        ),
+        |(name, args)| Token::FunctionCall {
+            name: name.into(),
+            args,
+        },
+    )
 }
 
 fn parens_macro_expansion(input: &str) -> IResult<&str, Token> {
-    delimited(tag("$("), macro_expansion_body(')'), tag(")"))(input)
+    delimited(
+        tag("$("),
+        alt((macro_expansion_body(')'), function_call_body(')'))),
+        tag(")"),
+    )(input)
 }
 
 fn braces_macro_expansion(input: &str) -> IResult<&str, Token> {
-    delimited(tag("${"), macro_expansion_body('}'), tag("}"))(input)
+    delimited(
+        tag("${"),
+        alt((macro_expansion_body('}'), function_call_body(')'))),
+        tag("}"),
+    )(input)
 }
 
 fn tiny_macro_expansion(input: &str) -> IResult<&str, Token> {
@@ -176,41 +217,30 @@ fn macro_expansion(input: &str) -> IResult<&str, Token> {
     ))(input)
 }
 
-fn text(input: &str) -> IResult<&str, Token> {
-    map(take_till1(|c| c == '$'), |x: &str| Token::Text(x.into()))(input)
-}
-
-fn text_but_not<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
-    map(take_till1(move |c| c == '$' || c == end), |x: &str| {
-        Token::Text(x.into())
-    })
+fn text_but_not<'a>(ends: Vec<char>) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
+    map(
+        take_till1(move |c| c == '$' || ends.contains(&c)),
+        |x: &str| Token::Text(x.into()),
+    )
 }
 
-fn single_token(input: &str) -> IResult<&str, Token> {
-    alt((text, macro_expansion))(input)
-}
-
-fn single_token_but_not<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
-    alt((text_but_not(end), macro_expansion))
+fn single_token_but_not<'a>(ends: Vec<char>) -> impl FnMut(&'a str) -> IResult<&'a str, Token> {
+    alt((text_but_not(ends), macro_expansion))
 }
 
 fn empty_tokens(input: &str) -> IResult<&str, TokenString> {
     map(tag(""), |_| TokenString(vec![Token::Text(String::new())]))(input)
 }
 
-fn tokens(input: &str) -> IResult<&str, TokenString> {
-    alt((map(many1(single_token), TokenString), empty_tokens))(input)
-}
-
-fn tokens_but_not<'a>(end: char) -> impl FnMut(&'a str) -> IResult<&'a str, TokenString> {
+fn tokens_but_not<'a>(ends: Vec<char>) -> impl FnMut(&'a str) -> IResult<&'a str, TokenString> {
     alt((
-        map(many1(single_token_but_not(end)), TokenString),
+        map(many1(single_token_but_not(ends)), TokenString),
         empty_tokens,
     ))
 }
 
 fn full_text_tokens(input: &str) -> IResult<&str, TokenString> {
-    all_consuming(tokens)(input)
+    all_consuming(tokens_but_not(vec![]))(input)
 }
 
 pub(crate) fn tokenize(input: &str) -> TokenString {