Support comment, empty/blank line, and whitespace

Author: DrSensor

.github/main.workflow

@@ -48,6 +48,7 @@ action "Perf cargo" {
 		"build --all",
 		"build -p scdlang-core",
 		"build -p scrap",
+		"build -p scdlang_xstate",
 	]
 }
 

examples/simple.scl

@@ -1,3 +1,11 @@
+    /// simple exmaple to test if it work
+	/// this example contain empty & blank line, whitespace, tab, oneline & block comment
+
+// without whitespace
 A->B
-B->C
-C->D
+
+// with whitespace
+B -> C
+	
+C/*for cheetah*/	->  D//for dimple
+    

packages/cli/src/commands/eval/mod.rs

@@ -37,6 +37,7 @@ impl<'c> CLI<'c> for Eval {
 			println!("Press Ctrl-D to exit and print the final results");
 		}
 
+		// TODO: change to https://docs.rs/linefeed
 		prompting();
 		for line in stdin.lock().lines() {
 			let expression = line.expect(Self::NAME);

packages/core/src/grammar.pest

@@ -2,15 +2,20 @@ DescriptionFile = { SOI ~ (
   NEWLINE? ~ (
     expression
   ) ~ NEWLINE?
-)+ ~ EOI }
+)* ~ EOI }
 
 expression = { StateName ~ transition }
 transition = { TransitionTo ~ StateName }
 
 // #region symbol
-TransitionTo = { "-"+ ~ ">" }
+TransitionTo = @{ "-"+ ~ ">" }
 // #endregion
 
 // #region name
-StateName = { ASCII_ALPHANUMERIC+ }
-// #endregion
+StateName = @{ ASCII_ALPHANUMERIC+ }
+// #endregion
+
+WHITESPACE = _{ " " | "\t" }
+COMMENT = _{ line_comment | block_comment }
+line_comment = _{ "//" ~ (!NEWLINE ~ ANY)* }
+block_comment = _{ "/*" ~ (block_comment|(!"*/" ~ ANY))* ~ "*/" }

packages/transpiler/xstate/src/ast/mod.rs

@@ -49,8 +49,12 @@ impl Machine {
 
 	pub fn from(source: &str) -> Result<Machine, MachineError> {
 		let mut parse_tree = scdlang::parse(&source)?;
-		let ast = Machine::from_pest(&mut parse_tree).expect("infallible");
-		Ok(ast)
+		if pairs::is_expression(&parse_tree) {
+			let line = &format!(r#"expression("{line}")"#, line = parse_tree.as_str());
+			Ok(Machine::from_pest(&mut parse_tree).expect(line))
+		} else {
+			Ok(Machine::default())
+		}
 	}
 
 	pub fn parse(&mut self, source: &str) -> Result<(), MachineError> {

packages/transpiler/xstate/src/ast/utils.rs

@@ -1,8 +1,27 @@
+use scdlang_core::Rule;
+
+pub mod pairs {
+	use super::*;
+	use pest::iterators::Pairs;
+
+	pub fn is_expression(pairs: &Pairs<Rule>) -> bool {
+		pairs
+			.peek()
+			.unwrap()
+			.into_inner()
+			.any(|pair| match pair.as_rule() {
+				Rule::expression => true,
+				_ => false,
+			})
+	}
+}
+
 pub mod span {
+	use super::*;
 	use crate::ast::Transition;
 	use from_pest::FromPest;
 	use pest::{Parser, Span};
-	use scdlang_core::{Rule, Scdlang};
+	use scdlang_core::Scdlang;
 	use serde_json::Value;
 	use std::collections::HashMap;