Fatal errors

- Makes errors fatal, so that a phase is only reached when all previous phases were error-free
- Parsing still recovers and can produce multiple errors
- Evaluation fails fast and can thus produce only a single error (except for parse errors due to an import)
- The single error that could occur during execution is removed for now
- Removes Value::Error variant

1 files changed, 40 insertions, 56 deletions

diff --git a/src/library/utility.rs b/src/library/utility.rs
index 4001d14f..fb39fce3 100644
--- a/src/library/utility.rs
+++ b/src/library/utility.rs
@@ -7,94 +7,78 @@ use crate::pretty::pretty;
 use super::*;
 
 /// `type`: The name of a value's type.
-pub fn type_(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
-    match args.expect::<Value>(ctx, "value") {
-        Some(value) => value.type_name().into(),
-        None => Value::Error,
-    }
+pub fn type_(_: &mut EvalContext, args: &mut FuncArgs) -> TypResult<Value> {
+    let value = args.expect::<Value>("value")?;
+    Ok(value.type_name().into())
 }
 
 /// `repr`: The string representation of a value.
-pub fn repr(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
-    match args.expect::<Value>(ctx, "value") {
-        Some(value) => pretty(&value).into(),
-        None => Value::Error,
-    }
+pub fn repr(_: &mut EvalContext, args: &mut FuncArgs) -> TypResult<Value> {
+    let value = args.expect::<Value>("value")?;
+    Ok(pretty(&value).into())
 }
 
 /// `len`: The length of a string, an array or a dictionary.
-pub fn len(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
-    match args.expect(ctx, "collection") {
-        Some(Spanned { v: Value::Str(v), .. }) => Value::Int(v.len() as i64),
-        Some(Spanned { v: Value::Array(v), .. }) => Value::Int(v.len() as i64),
-        Some(Spanned { v: Value::Dict(v), .. }) => Value::Int(v.len() as i64),
-        Some(other) if other.v != Value::Error => {
-            ctx.diag(error!(other.span, "expected string, array or dictionary"));
-            Value::Error
-        }
-        _ => Value::Error,
-    }
+pub fn len(_: &mut EvalContext, args: &mut FuncArgs) -> TypResult<Value> {
+    let Spanned { v, span } = args.expect("collection")?;
+    Ok(match v {
+        Value::Str(v) => Value::Int(v.len() as i64),
+        Value::Array(v) => Value::Int(v.len() as i64),
+        Value::Dict(v) => Value::Int(v.len() as i64),
+        _ => bail!(args.file, span, "expected string, array or dictionary"),
+    })
 }
 
 /// `rgb`: Create an RGB(A) color.
-pub fn rgb(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
-    Value::Color(Color::Rgba(
+pub fn rgb(_: &mut EvalContext, args: &mut FuncArgs) -> TypResult<Value> {
+    Ok(Value::Color(Color::Rgba(
         if let Some(string) = args.eat::<Spanned<EcoString>>() {
             match RgbaColor::from_str(&string.v) {
                 Ok(color) => color,
-                Err(_) => {
-                    ctx.diag(error!(string.span, "invalid color"));
-                    return Value::Error;
-                }
+                Err(_) => bail!(args.file, string.span, "invalid color"),
             }
         } else {
-            let r = args.expect(ctx, "red component").unwrap_or(0.0);
-            let g = args.expect(ctx, "green component").unwrap_or(0.0);
-            let b = args.expect(ctx, "blue component").unwrap_or(0.0);
+            let r = args.expect("red component")?;
+            let g = args.expect("green component")?;
+            let b = args.expect("blue component")?;
             let a = args.eat().unwrap_or(1.0);
             let f = |v: f64| (v.clamp(0.0, 1.0) * 255.0).round() as u8;
             RgbaColor::new(f(r), f(g), f(b), f(a))
         },
-    ))
+    )))
 }
 
 /// `min`: The minimum of a sequence of values.
-pub fn min(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
-    minmax(ctx, args, Ordering::Less)
+pub fn min(_: &mut EvalContext, args: &mut FuncArgs) -> TypResult<Value> {
+    minmax(args, Ordering::Less)
 }
 
 /// `max`: The maximum of a sequence of values.
-pub fn max(ctx: &mut EvalContext, args: &mut FuncArgs) -> Value {
-    minmax(ctx, args, Ordering::Greater)
+pub fn max(_: &mut EvalContext, args: &mut FuncArgs) -> TypResult<Value> {
+    minmax(args, Ordering::Greater)
 }
 
 /// Find the minimum or maximum of a sequence of values.
-fn minmax(ctx: &mut EvalContext, args: &mut FuncArgs, goal: Ordering) -> Value {
-    let span = args.span;
-    let mut extremum = None;
+fn minmax(args: &mut FuncArgs, goal: Ordering) -> TypResult<Value> {
+    let &mut FuncArgs { file, span, .. } = args;
 
+    let mut extremum = args.expect::<Value>("value")?;
     for value in args.all::<Value>() {
-        if let Some(prev) = &extremum {
-            match value.partial_cmp(&prev) {
-                Some(ordering) if ordering == goal => extremum = Some(value),
-                Some(_) => {}
-                None => {
-                    ctx.diag(error!(
-                        span,
-                        "cannot compare {} with {}",
-                        prev.type_name(),
-                        value.type_name(),
-                    ));
-                    return Value::Error;
+        match value.partial_cmp(&extremum) {
+            Some(ordering) => {
+                if ordering == goal {
+                    extremum = value;
                 }
             }
-        } else {
-            extremum = Some(value);
+            None => bail!(
+                file,
+                span,
+                "cannot compare {} with {}",
+                extremum.type_name(),
+                value.type_name(),
+            ),
         }
     }
 
-    extremum.unwrap_or_else(|| {
-        args.expect::<Value>(ctx, "value");
-        Value::Error
-    })
+    Ok(extremum)
 }