Implement parser in pest

Cargo.toml

@@ -17,12 +17,12 @@ path = "src/main.rs"
 
 [dependencies]
 rustyline = { version = "10.0.0", optional = true }
-nom = { version = "7", default-features = false, features = ["alloc"] }
-nom_locate = { version = "4.0.0", default-features = false, features = ["alloc"] }
 clap = { version = "4.3.11", features = ["derive"], optional = true }
 colored = { version = "2.0.4", optional = true }
 humantime = { version = "2.1.0", optional = true }
+pest = { version = "2.7.14", features = [], default-features = false }
+pest_derive = { version = "2.7.14", features = [], default-features = false }
 
 [features]
 default = ["std"]
-std = [ "rustyline", "clap", "colored", "humantime" ]
+std = [ "rustyline", "clap", "colored", "humantime", "pest/std", "pest_derive/std" ]

examples/capav.lsh

@@ -1,9 +1,9 @@
 term1 := (\x y . y x) (y y) z;
 term2 := (\x y . y x) (a a) z;
 
-@echo "This works as expected:"
+@echo "This works as expected:";
 !debug (!vnormalize term2);
 
-@echo ""
-@echo "But here we see the necessity of capture avoidance:"
+@echo "";
+@echo "But here we see the necessity of capture avoidance:";
 !debug (!vnormalize term1);

examples/fib.lsh

@@ -1,6 +1,6 @@
-@usestd
-@set strategy normal
-@set numerals true
+@usestd;
+@set strategy normal;
+@set numerals true;
 
 iszero := λn.n (λx. FALSE) TRUE;
 
@@ -13,6 +13,6 @@ fib' := \f x. IFTHENELSE
 			(ADD (f f (PRED x)) (f f (PRED (PRED x)))));
 fib := fib' fib';
 
-@echo ""
-@echo "6. Fibonacci number"
+@echo "";
+@echo "6. Fibonacci number";
 listunsorted := !debug (!cnorm (fib $6));

examples/sort.lsh

@@ -1,5 +1,5 @@
-@set strategy normal
-@usestd
+@set strategy normal;
+@usestd;
 
 
 one := !n (SUCC NIL);
@@ -34,11 +34,11 @@ sort' := \f l. IFTHENELSE
 sort := sort' sort';
 
 
-@echo ""
-@echo "Unsorted list:"
+@echo "";
+@echo "Unsorted list:";
 listunsorted := !debug (!norm (CONS three (CONS one (CONS four ((CONS two NIL))))));
 
-@echo ""
-@echo "After sorting:"
+@echo "";
+@echo "After sorting:";
 !debug (!time (!cnorm (sort listunsorted)));
 

src/error.rs

@@ -3,9 +3,10 @@ extern crate alloc;
 use alloc::borrow::ToOwned;
 use alloc::format;
 use alloc::string::{String, ToString};
+use pest::RuleType;
 use core::fmt::Display;
 
-use crate::{parsing, r#macro::Macro};
+use crate::r#macro::Macro;
 
 pub type LashResult<T> = Result<T, LashError>;
 
@@ -25,6 +26,7 @@ pub enum LashErrorType {
     SetKeyError,
     SetValueError,
     SyntaxError,
+    UnknownMacroError,
     #[cfg(not(feature = "std"))]
     NotFoundError,
     #[cfg(not(feature = "std"))]
@@ -66,6 +68,13 @@ impl LashError {
         }
     }
 
+    pub fn new_syntax_error<T: RuleType>(err: pest::error::Error<T>) -> Self {
+        LashError {
+            error_type: LashErrorType::SyntaxError,
+            message: format!("\n{}", err),
+        }
+    }
+
     pub fn new_set_key_error(key: &str) -> Self {
         LashError {
             error_type: LashErrorType::SetKeyError,
@@ -80,6 +89,13 @@ impl LashError {
         }
     }
 
+    pub fn new_unknown_macro_error(name: &str) -> Self {
+        LashError {
+            error_type: LashErrorType::UnknownMacroError,
+            message: format!("unknown macro '{}'", name),
+        }
+    }
+
     #[cfg(not(feature = "std"))]
     pub fn new_not_supported_error(message: String) -> Self {
         LashError {
@@ -108,9 +124,10 @@ impl Display for LashError {
             FileError => "File Error",
             FormatError => "Format Error",
             MacroArgError => "Macro Argument Error",
+            SyntaxError => "Syntax Error",
             SetKeyError => "Set Key Error",
             SetValueError => "Set Value Error",
-            SyntaxError => "Syntax Error",
+            UnknownMacroError => "Unknown Macro Error",
             #[cfg(not(feature = "std"))]
             NotFoundError => "Not Found",
             #[cfg(not(feature = "std"))]
@@ -120,21 +137,6 @@ impl Display for LashError {
     }
 }
 
-impl From<nom::Err<parsing::ParseError<'_>>> for LashError {
-    fn from(value: nom::Err<parsing::ParseError<'_>>) -> Self {
-        use nom::Err::*;
-        let message = match value {
-            Incomplete(_) => "incomplete data".to_owned(),
-            Error(e) => format!("{}", e),
-            Failure(e) => format!("{}", e),
-        };
-        LashError {
-            error_type: LashErrorType::SyntaxError,
-            message,
-        }
-    }
-}
-
 impl From<core::fmt::Error> for LashError {
     fn from(value: core::fmt::Error) -> Self {
         LashError {