Rename Span to SourceSpan and switch it to offset+length based repres…

…entation;

ergotree-interpreter/src/eval/error.rs

@@ -3,7 +3,7 @@ use ergotree_ir::ergo_tree::ErgoTreeError;
 use ergotree_ir::mir::constant::TryExtractFromError;
 use ergotree_ir::serialization::SigmaParsingError;
 use ergotree_ir::serialization::SigmaSerializationError;
-use ergotree_ir::source_span::Span;
+use ergotree_ir::source_span::SourceSpan;
 use sigma_ser::ScorexParsingError;
 use sigma_ser::ScorexSerializationError;
 use thiserror::Error;
@@ -78,7 +78,7 @@ pub enum EvalError {
 #[derive(PartialEq, Eq, Debug, Clone)]
 pub struct EvalErrorDetails {
     /// source span
-    source_span: Span,
+    source_span: SourceSpan,
     /// environment after evaluation
     env: Env,
     /// source code
@@ -87,7 +87,7 @@ pub struct EvalErrorDetails {
 
 impl EvalError {
     /// Wrap eval error with source span
-    pub fn wrap(self, source_span: Span, env: Env) -> Self {
+    pub fn wrap(self, source_span: SourceSpan, env: Env) -> Self {
         EvalError::Wrapped {
             error: Box::new(self),
             details: EvalErrorDetails {
@@ -112,7 +112,7 @@ impl EvalError {
             e => EvalError::Wrapped {
                 error: Box::new(e),
                 details: EvalErrorDetails {
-                    source_span: Span::empty(),
+                    source_span: SourceSpan::empty(),
                     env: Env::empty(),
                     source: Some(source),
                 },
@@ -122,11 +122,11 @@ impl EvalError {
 }
 
 pub trait ExtResultEvalError<T> {
-    fn enrich_err(self, span: Span, env: Env) -> Result<T, EvalError>;
+    fn enrich_err(self, span: SourceSpan, env: Env) -> Result<T, EvalError>;
 }
 
 impl<T> ExtResultEvalError<T> for Result<T, EvalError> {
-    fn enrich_err(self, span: Span, env: Env) -> Result<T, EvalError> {
+    fn enrich_err(self, span: SourceSpan, env: Env) -> Result<T, EvalError> {
         self.map_err(|e| e.wrap(span, env))
     }
 }

ergotree-ir/src/pretty_printer.rs

@@ -10,7 +10,7 @@ use crate::mir::constant::Constant;
 use crate::mir::expr::Expr;
 use crate::mir::val_def::ValDef;
 use crate::mir::val_use::ValUse;
-use crate::source_span::Span;
+use crate::source_span::SourceSpan;
 use crate::source_span::Spanned;
 
 /// Print error
@@ -29,7 +29,7 @@ pub trait Print {
 
 impl Print for BlockValue {
     fn print(&self, w: &mut dyn Printer) -> Result<Expr, PrintError> {
-        let start = w.current_pos();
+        let offset = w.current_pos();
         writeln!(w, "{{")?;
         w.inc_ident();
         let indent = w.get_indent();
@@ -43,9 +43,9 @@ impl Print for BlockValue {
         self.result.print(w)?;
         w.dec_ident();
         writeln!(w, "\n}}")?;
-        let end = w.current_pos();
+        let length = w.current_pos() - offset;
         Ok(Spanned {
-            source_span: Span { start, end },
+            source_span: SourceSpan { offset, length },
             expr: self.clone(),
         }
         .into())
@@ -54,12 +54,12 @@ impl Print for BlockValue {
 
 impl Print for ValDef {
     fn print(&self, w: &mut dyn Printer) -> Result<Expr, PrintError> {
-        let start = w.current_pos();
+        let offset = w.current_pos();
         write!(w, "val v{} = ", self.id)?;
         self.rhs.print(w)?;
-        let end = w.current_pos();
+        let length = w.current_pos() - offset;
         Ok(Spanned {
-            source_span: Span { start, end },
+            source_span: SourceSpan { offset, length },
             expr: self.clone(),
         }
         .into())
@@ -83,14 +83,14 @@ impl Print for ValUse {
 
 impl Print for Append {
     fn print(&self, w: &mut dyn Printer) -> Result<Expr, PrintError> {
-        let start = w.current_pos();
+        let offset = w.current_pos();
         self.input.print(w)?;
         write!(w, ".append(")?;
         self.col_2.print(w)?;
         write!(w, ")")?;
-        let end = w.current_pos();
+        let length = w.current_pos() - offset;
         Ok(Spanned {
-            source_span: Span { start, end },
+            source_span: SourceSpan { offset, length },
             expr: self.clone(),
         }
         .into())

ergotree-ir/src/source_span.rs

@@ -1,31 +1,35 @@
 //! Source position for an IR node in the source code
 
-use crate::mir::val_def::ValDef;
 use crate::mir::block::BlockValue;
 use crate::mir::coll_append::Append;
 use crate::mir::expr::Expr;
+use crate::mir::val_def::ValDef;
 
 /// Source position for the Expr
 #[derive(PartialEq, Eq, Debug, Clone)]
-pub struct Span {
-    /// Start position in the source code
-    pub start: usize,
-    /// End position in the source code
-    pub end: usize,
+pub struct SourceSpan {
+    /// Start position in the span
+    pub offset: usize,
+    /// The length of the span
+    pub length: usize,
 }
 
-impl Span {
+impl SourceSpan {
     /// Empty span
     pub fn empty() -> Self {
-        Span { start: 0, end: 0 }
+        SourceSpan {
+            offset: 0,
+            length: 0,
+        }
     }
 }
 
+
 /// Wrapper for Expr with source position
 #[derive(PartialEq, Eq, Debug, Clone)]
 pub struct Spanned<T> {
     /// Source position
-    pub source_span: Span,
+    pub source_span: SourceSpan,
     /// Wrapped value
     pub expr: T,
 }
@@ -42,7 +46,7 @@ macro_rules! into_expr {
         impl From<$variant> for Expr {
             fn from(v: $variant) -> Self {
                 Expr::$variant(Spanned {
-                    source_span: Span::empty(),
+                    source_span: SourceSpan::empty(),
                     expr: v,
                 })
             }
@@ -57,7 +61,7 @@ into_expr!(ValDef);
 impl<T> From<T> for Spanned<T> {
     fn from(v: T) -> Self {
         Spanned {
-            source_span: Span::empty(),
+            source_span: SourceSpan::empty(),
             expr: v,
         }
     }
@@ -66,7 +70,7 @@ impl<T> From<T> for Spanned<T> {
 impl Expr {
     /// Source span for the Expr
     #[allow(clippy::todo)]
-    pub fn span(&self) -> &Span {
+    pub fn span(&self) -> &SourceSpan {
         match self {
             Expr::Append(op) => &op.source_span,
             Expr::Const(_) => todo!(),