Adds reusable RawValueExpr::resolve method (#854)

src/lazy/decoder.rs

@@ -18,8 +18,8 @@ use crate::lazy::streaming_raw_reader::RawReaderState;
 use crate::read_config::ReadConfig;
 use crate::result::IonFailure;
 use crate::{
-    v1_0, v1_1, Catalog, Encoding, IonResult, IonType, LazyExpandedFieldName, LazyRawWriter,
-    RawSymbolRef, ValueRef,
+    v1_0, v1_1, Catalog, Encoding, IonResult, IonType, LazyExpandedFieldName, LazyExpandedValue,
+    LazyRawWriter, MacroExpr, RawSymbolRef, ValueExpr, ValueRef,
 };
 
 pub trait HasSpan<'top>: HasRange {
@@ -205,6 +205,28 @@ impl<V: Debug, M: Debug> RawValueExpr<V, M> {
     }
 }
 
+impl<V, M> RawValueExpr<V, M> {
+    pub fn resolve<'top, D>(
+        self,
+        context: EncodingContextRef<'top>,
+    ) -> IonResult<ValueExpr<'top, D>>
+    where
+        V: LazyRawValue<'top, D>,
+        M: RawEExpression<'top, D>,
+        D: Decoder<Value<'top> = V, EExp<'top> = M>,
+    {
+        let expr = match self {
+            RawValueExpr::ValueLiteral(value) => {
+                ValueExpr::ValueLiteral(LazyExpandedValue::from_literal(context, value))
+            }
+            RawValueExpr::EExp(invocation) => {
+                ValueExpr::MacroInvocation(MacroExpr::from_eexp(invocation.resolve(context)?))
+            }
+        };
+        Ok(expr)
+    }
+}
+
 impl<V: HasRange, M: HasRange> HasRange for RawValueExpr<V, M> {
     fn range(&self) -> Range<usize> {
         match self {

src/lazy/expanded/e_expression.rs

@@ -18,7 +18,7 @@ use crate::lazy::expanded::template::TemplateMacroRef;
 use crate::lazy::expanded::{EncodingContextRef, LazyExpandedValue};
 use crate::lazy::text::raw::v1_1::arg_group::{EExpArg, EExpArgExpr};
 use crate::lazy::text::raw::v1_1::reader::MacroIdRef;
-use crate::{try_next, Environment, HasRange, HasSpan, IonResult, Span};
+use crate::{try_next, try_or_some_err, Environment, HasRange, HasSpan, IonResult, Span};
 
 /// An `ArgGroup` is a collection of expressions found in e-expression argument position.
 /// They can only appear in positions that correspond with variadic parameters.
@@ -323,20 +323,8 @@ impl<'top, D: Decoder> Iterator for EExpArgGroupIterator<'top, D> {
     type Item = IonResult<ValueExpr<'top, D>>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        let expr = try_next!(self.expressions.next());
-        match expr {
-            RawValueExpr::ValueLiteral(v) => Some(Ok(ValueExpr::ValueLiteral(
-                LazyExpandedValue::from_literal(self.context, v),
-            ))),
-            RawValueExpr::EExp(e) => {
-                let resolved_eexp = match e.resolve(self.context) {
-                    Ok(eexp) => eexp,
-                    Err(e) => return Some(Err(e)),
-                };
-                Some(Ok(ValueExpr::MacroInvocation(MacroExpr::from_eexp(
-                    resolved_eexp,
-                ))))
-            }
-        }
+        let raw_expr: RawValueExpr<_, _> = try_next!(self.expressions.next());
+        let expr = try_or_some_err!(raw_expr.resolve(self.context));
+        Some(Ok(expr))
     }
 }

src/lazy/expanded/sequence.rs

@@ -1,5 +1,5 @@
 use crate::element::iterators::SymbolsIterator;
-use crate::lazy::decoder::{Decoder, LazyRawSequence, LazyRawValueExpr, RawValueExpr};
+use crate::lazy::decoder::{Decoder, LazyRawSequence, LazyRawValueExpr};
 use crate::lazy::expanded::macro_evaluator::{
     MacroEvaluator, MacroExprArgsIterator, RawEExpression, ValueExpr,
 };
@@ -396,34 +396,9 @@ fn expand_next_sequence_value<'top, D: Decoder>(
     evaluator: &mut MacroEvaluator<'top, D>,
     iter: &mut impl Iterator<Item = IonResult<LazyRawValueExpr<'top, D>>>,
 ) -> Option<IonResult<LazyExpandedValue<'top, D>>> {
-    loop {
-        // If the evaluator's stack is not empty, it's still expanding a macro.
-        if !evaluator.is_empty() {
-            let value = evaluator.next().transpose();
-            if value.is_some() {
-                // The `Some` may contain a value or an error; either way, that's the next return value.
-                return value;
-            }
-            // It's possible for a macro to produce zero values. If that happens, we continue on to
-            // pull another expression from the list iterator.
-        }
-
-        match iter.next() {
-            None => return None,
-            Some(Ok(RawValueExpr::ValueLiteral(value))) => {
-                return Some(Ok(LazyExpandedValue::from_literal(context, value)))
-            }
-            Some(Ok(RawValueExpr::EExp(invocation))) => {
-                let resolved_invocation = match invocation.resolve(context) {
-                    Ok(resolved) => resolved,
-                    Err(e) => return Some(Err(e)),
-                };
-                evaluator.push(try_or_some_err!(resolved_invocation.expand()));
-                continue;
-            }
-            Some(Err(e)) => return Some(Err(e)),
-        }
-    }
+    let mut resolving_iter =
+        iter.map(|result| result.and_then(|raw_expr| raw_expr.resolve(context)));
+    expand_next_sequence_value_from_resolved(evaluator, &mut resolving_iter)
 }
 
 fn expand_next_sequence_value_from_resolved<'top, D: Decoder>(

src/lazy/sequence.rs

@@ -140,7 +140,7 @@ impl<'top, D: Decoder> TryFrom<LazyList<'top, D>> for Sequence {
     fn try_from(lazy_sequence: LazyList<'top, D>) -> Result<Self, Self::Error> {
         let sequence: Sequence = lazy_sequence
             .iter()
-            .map(|v| Element::try_from(v?))
+            .map(|result| result.and_then(Element::try_from))
             .collect::<IonResult<Vec<_>>>()?
             .into();
         Ok(sequence)