Unified error struct

schala-lang/language/src/error.rs

@@ -0,0 +1,99 @@
+use crate::schala::{SourceReference, Stage};
+use crate::source_map::Location;
+use crate::tokenizing::{Token, TokenKind};
+use crate::parsing::ParseError;
+use crate::typechecking::TypeError;
+
+pub struct SchalaError {
+  errors: Vec<Error>,
+  //TODO unify these sometime
+  formatted_parse_error: Option<String>,
+}
+
+impl SchalaError {
+
+  pub(crate) fn display(&self) -> String {
+    if let Some(ref err) = self.formatted_parse_error {
+      err.clone()
+    } else {
+      self.errors[0].text.as_ref().cloned().unwrap_or_default()
+    }
+  }
+
+  pub(crate) fn from_type_error(err: TypeError) -> Self {
+    Self {
+      formatted_parse_error: None,
+      errors: vec![
+        Error { location: None, text: Some(err.msg), stage: Stage::Typechecking }
+      ]
+    }
+  }
+
+  pub(crate) fn from_string(text: String, stage: Stage) -> Self {
+    Self {
+      formatted_parse_error: None,
+      errors: vec![
+        Error { location: None, text: Some(text), stage }
+      ]
+    }
+  }
+
+  pub(crate) fn from_parse_error(parse_error: ParseError, source_reference: &SourceReference) -> Self {
+    Self {
+      formatted_parse_error: Some(format_parse_error(parse_error, source_reference)),
+      errors: vec![],
+    }
+  }
+
+  pub(crate) fn from_tokens(tokens: &[Token]) -> Option<SchalaError> {
+    let token_errors: Vec<Error> = tokens.iter()
+      .filter_map(|tok| match tok.kind {
+        TokenKind::Error(ref err) => Some(Error {
+          location: Some(tok.location),
+          text: Some(err.clone()),
+          stage: Stage::Tokenizing,
+        }),
+        _ => None
+      }).collect();
+
+    if token_errors.is_empty() {
+      None
+    } else {
+      Some(SchalaError {
+        errors: token_errors,
+        formatted_parse_error: None,
+      })
+    }
+  }
+}
+
+#[allow(dead_code)]
+struct Error {
+  location: Option<Location>,
+  text: Option<String>,
+  stage: Stage,
+}
+
+
+fn format_parse_error(error: ParseError, source_reference: &SourceReference) -> String {
+  let line_num = error.token.location.line_num;
+  let ch = error.token.location.char_num;
+  let line_from_program = source_reference.get_line(line_num);
+  let location_pointer = format!("{}^", " ".repeat(ch));
+
+  let line_num_digits = format!("{}", line_num).chars().count();
+  let space_padding = " ".repeat(line_num_digits);
+
+  let production = match error.production_name {
+    Some(n) => format!("\n(from production \"{}\")", n),
+    None => "".to_string()
+  };
+
+  format!(r#"
+{error_msg}{production}
+{space_padding} |
+{line_num} | {}
+{space_padding} | {}
+"#, line_from_program, location_pointer, error_msg=error.msg, space_padding=space_padding, line_num=line_num, production=production
+)
+}

schala-lang/language/src/lib.rs

@@ -31,6 +31,7 @@ mod builtin;
 mod reduced_ast;
 mod eval;
 mod source_map;
+mod error;
 
 mod schala;
 

schala-lang/language/src/schala.rs

@@ -7,6 +7,7 @@ use schala_repl::{ProgrammingLanguageInterface,
 ComputationRequest, ComputationResponse,
 LangMetaRequest, LangMetaResponse, GlobalOutputStats};
 use crate::{reduced_ast, tokenizing, parsing, eval, typechecking, symbol_table, source_map};
+use crate::error::SchalaError;
 
 pub type SymbolTableHandle = Rc<RefCell<symbol_table::SymbolTable>>;
 pub type SourceMapHandle = Rc<RefCell<source_map::SourceMap>>;
@@ -60,8 +61,8 @@ impl Schala {
     let mut env = Schala::new_blank_env();
 
     let response = env.run_pipeline(prelude);
-    if let Err(msg) = response {
-      panic!("Error in prelude, panicking: {}", msg);
+    if let Err(err) = response {
+      panic!("Error in prelude, panicking: {}", err.display());
     }
     env
   }
@@ -69,36 +70,33 @@ impl Schala {
   /// This is where the actual action of interpreting/compilation happens.
   /// Note: this should eventually use a query-based system for parallelization, cf.
   /// https://rustc-dev-guide.rust-lang.org/overview.html
-  fn run_pipeline(&mut self, source: &str) -> Result<String, String> {
-    //TODO `run_pipeline` should return a formatted error struct
-
-    //TODO every stage should have a common error-format that gets turned into a repl-appropriate
-    //string in `run_computation`
+  fn run_pipeline(&mut self, source: &str) -> Result<String, SchalaError> {
     // 1st stage - tokenization
     // TODO tokenize should return its own error type
     let tokens = tokenizing::tokenize(source);
-    let token_errors: Vec<String> = tokens.iter().filter_map(|t| t.get_error()).collect();
-    if token_errors.len() > 0 {
-      return Err(format!("{:?}", token_errors));
+    if let Some(err) = SchalaError::from_tokens(&tokens) {
+      return Err(err)
     }
 
     //2nd stage - parsing
     self.active_parser.add_new_tokens(tokens);
     let mut ast = self.active_parser.parse()
-      .map_err(|err| format_parse_error(err, &self.source_reference))?;
+      .map_err(|err| SchalaError::from_parse_error(err, &self.source_reference))?;
 
     // Symbol table
-    self.symbol_table.borrow_mut().add_top_level_symbols(&ast)?;
+    self.symbol_table.borrow_mut().add_top_level_symbols(&ast)
+      .map_err(|err| SchalaError::from_string(err, Stage::Symbols))?;
 
     // Scope resolution - requires mutating AST
-    self.resolver.resolve(&mut ast)?;
+    self.resolver.resolve(&mut ast)
+      .map_err(|err| SchalaError::from_string(err, Stage::ScopeResolution))?;
 
     // Typechecking
     // TODO typechecking not working
     let _overall_type = self.type_context.typecheck(&ast)
-      .map_err(|err| format!("Type error: {}", err.msg));
+      .map_err(|err| SchalaError::from_type_error(err));
 
-    // Reduce AST - this doesn't produce an error yet, but probably should
+    // Reduce AST - TODO this doesn't produce an error yet, but probably should
     let symbol_table = self.symbol_table.borrow();
     let reduced_ast = reduced_ast::reduce(&ast, &symbol_table);
 
@@ -108,6 +106,9 @@ impl Schala {
       .into_iter()
       .collect();
 
+    let text_output: Result<Vec<String>, SchalaError> = text_output
+      .map_err(|err| SchalaError::from_string(err, Stage::Evaluation));
+
     let eval_output: String = text_output
       .map(|v| { Iterator::intersperse(v.into_iter(), "\n".to_owned()).collect() })?;
 
@@ -115,31 +116,9 @@ impl Schala {
   }
 }
 
-fn format_parse_error(error: parsing::ParseError, source_reference: &SourceReference) -> String {
-  let line_num = error.token.location.line_num;
-  let ch = error.token.location.char_num;
-  let line_from_program = source_reference.get_line(line_num);
-  let location_pointer = format!("{}^", " ".repeat(ch));
-
-  let line_num_digits = format!("{}", line_num).chars().count();
-  let space_padding = " ".repeat(line_num_digits);
-
-  let production = match error.production_name {
-    Some(n) => format!("\n(from production \"{}\")", n),
-    None => "".to_string()
-  };
-
-  format!(r#"
-{error_msg}{production}
-{space_padding} |
-{line_num} | {}
-{space_padding} | {}
-"#, line_from_program, location_pointer, error_msg=error.msg, space_padding=space_padding, line_num=line_num, production=production
-)
-}
 
 /// Represents lines of source code
-struct SourceReference {
+pub(crate) struct SourceReference {
   lines: Option<Vec<String>>
 }
 
@@ -152,11 +131,23 @@ impl SourceReference {
     //TODO this is a lot of heap allocations - maybe there's a way to make it more efficient?
     self.lines = Some(source.lines().map(|s| s.to_string()).collect()); }
 
-  fn get_line(&self, line: usize) -> String {
+  pub fn get_line(&self, line: usize) -> String {
     self.lines.as_ref().and_then(|x| x.get(line).map(|s| s.to_string())).unwrap_or(format!("NO LINE FOUND"))
   }
 }
 
+#[allow(dead_code)]
+#[derive(Clone, Copy, Debug)]
+pub(crate) enum Stage {
+  Tokenizing,
+  Parsing,
+  Symbols,
+  ScopeResolution,
+  Typechecking,
+  AstReduction,
+  Evaluation,
+}
+
 fn stage_names() -> Vec<&'static str> {
   vec![
     "tokenizing",
@@ -185,7 +176,8 @@ impl ProgrammingLanguageInterface for Schala {
     self.source_reference.load_new_source(source);
     let sw = Stopwatch::start_new();
 
-    let main_output = self.run_pipeline(source);
+    let main_output = self.run_pipeline(source)
+      .map_err(|schala_err| schala_err.display());
 
     let global_output_stats = GlobalOutputStats {
       total_duration: sw.elapsed(),

schala-lang/language/src/tokenizing.rs

@@ -99,12 +99,6 @@ pub struct Token {
 }
 
 impl Token {
-  pub fn get_error(&self) -> Option<String> {
-    match self.kind {
-      TokenKind::Error(ref s) => Some(s.clone()),
-      _ => None,
-    }
-  }
   pub fn to_string_with_metadata(&self) -> String {
     format!("{}({})", self.kind, self.location)
   }