Support for encoding directives, arg groups, length-prefixed e-expres…

…sions (#796)

* Adds EncodingDirective variant to SystemStreamItem
* Adds support for switching encodings midstream
* Adds support for parameter cardinality modifiers
* Adds support for reading argument groups
* Adds support for length-prefixed e-expressions
* Optimizes and simplifies macro evaluation
* Simplifies struct expansion logic
* Adds static analysis optimizations to template evaluation
* Adds support for lazily evaluating top-level e-expressions
* Adds more Ion 1.1 encodings to the `read_many_structs` benchmark
* Shrinks many data types

Cargo.toml

@@ -21,7 +21,7 @@ edition = "2021"
 # We need at least 1.65 for GATs[1] and 1.67 for `ilog`[2]
 # [1] https://blog.rust-lang.org/2022/11/03/Rust-1.65.0.html
 # [2] https://blog.rust-lang.org/2023/01/26/Rust-1.67.0.html#stabilized-apis
-rust-version = "1.67"
+rust-version = "1.77"
 
 [features]
 default = []
@@ -63,6 +63,7 @@ smallvec = { version = "1.9.0", features = ["const_generics"] }
 bumpalo = { version = "3.15.3", features = ["collections", "std"] }
 digest = { version = "0.9", optional = true }
 ice_code = "0.1.4"
+rustc-hash = "2.0.0"
 sha2 = { version = "0.9", optional = true }
 serde = { version = "1.0", features = ["derive"], optional = true }
 serde_with = { version = "3.7.0", optional = true }

benches/write_many_structs.rs

@@ -42,7 +42,7 @@ mod benchmark {
                 &[
                     black_box("SUCCESS"),
                     black_box("example-client-1"),
-                    black_box("aws-us-east-5f-18b4fa"),
+                    black_box("aws-us-east-5f-abc-123"),
                     black_box("region 4"),
                     black_box("2022-12-07T20:59:59.744000Z"),
                 ],
@@ -73,7 +73,7 @@ mod benchmark {
                     symbol_id(black_box(21)),
                     // $22 = example-client-1
                     symbol_id(black_box(22)),
-                    // $23 = aws-us-east-5f-18b4fa
+                    // $23 = aws-us-east-5f-abc-123
                     symbol_id(black_box(23)),
                     // $24 = region 4
                     symbol_id(black_box(24)),
@@ -92,7 +92,7 @@ mod benchmark {
             // them wouldn't be beneficial.
             .write(black_box("6"))? // thread_name
             .write(black_box("1"))? // client_num
-            .write(symbol_id(black_box(10)))?; // host_id: "18b4fa" ($10)
+            .write(symbol_id(black_box(10)))?; // host_id: "abc-123" ($10)
         let mut nested_eexp = eexp.eexp_writer(1)?;
         nested_eexp
             // $11 = region 4
@@ -109,7 +109,7 @@ mod benchmark {
             .write(black_box(418))? // thread_id
             .write(black_box("6"))? // thread_name
             .write(black_box("1"))? // client_num
-            .write(black_box("18b4fa"))?; // host_id
+            .write(black_box("abc-123"))?; // host_id
         let mut nested_eexp = eexp.eexp_writer(1)?;
         nested_eexp
             .write(black_box("region 4"))?

src/element/sequence.rs

@@ -6,17 +6,34 @@ use crate::lazy::encoding::Encoding;
 use crate::write_config::WriteConfig;
 use crate::IonResult;
 use std::cmp::Ordering;
+use std::fmt::{Debug, Formatter};
 use std::io;
 
 /// An iterable, addressable series of Ion [`Element`]s.
 ///
 /// A `Sequence` is not itself an Ion value type, but can represent a series of Ion values appearing
 /// in a [`List`](crate::List), a [`SExp`](crate::SExp), or at the top level.
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Clone, PartialEq, Eq)]
 pub struct Sequence {
     elements: Vec<Element>,
 }
 
+impl Debug for Sequence {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Sequence<")?;
+        let mut is_first = true;
+        for element in self {
+            if is_first {
+                write!(f, "{element}")?;
+            } else {
+                write!(f, ", {element}")?;
+                is_first = false;
+            }
+        }
+        write!(f, ">")
+    }
+}
+
 impl Sequence {
     pub fn new<E: Into<Element>, I: IntoIterator<Item = E>>(elements: I) -> Sequence {
         let elements = elements.into_iter().map(|e| e.into()).collect();