Add methods for reading borrowed strings

This initial implementation is possibly not very clean and causes quite
some code duplication in `reader.rs`; ideally this should be improved in
the future, if possible.

Resolves #1

Author: Marcono1234

README.md

@@ -46,7 +46,7 @@ let json = r#"{"a": [1, true]}"#;
 let mut json_reader = JsonStreamReader::new(json.as_bytes());
 
 json_reader.begin_object()?;
-assert_eq!(json_reader.next_name()?, "a");
+assert_eq!("a", json_reader.next_name()?);
 
 json_reader.begin_array()?;
 assert_eq!(1_u32, json_reader.next_number()??);

benches/reader_benchmark.rs

@@ -90,10 +90,10 @@ fn bench_compare(c: &mut Criterion, name: &str, json: &str) {
                     stack.push(StackValue::Object)
                 }
                 ValueType::String => {
-                    json_reader.next_string()?;
+                    json_reader.next_str()?;
                 }
                 ValueType::Number => {
-                    json_reader.next_number_as_string()?;
+                    json_reader.next_number_as_str()?;
                 }
                 ValueType::Boolean => {
                     json_reader.next_bool()?;
@@ -178,13 +178,13 @@ fn benchmark_large_array(c: &mut Criterion) {
             .repeat(1000)
             .as_str()
         + "true]";
-    bench_compare(c, "read-large-array", json.as_str());
+    bench_compare(c, "read-large-array", &json);
 }
 
 fn benchmark_nested_object(c: &mut Criterion) {
     let count = 1000;
     let json = r#"{"member name":"#.repeat(count) + "true" + "}".repeat(count).as_str();
-    bench_compare(c, "read-nested-object", json.as_str());
+    bench_compare(c, "read-nested-object", &json);
 }
 
 fn benchmark_nested_object_pretty(c: &mut Criterion) {
@@ -202,7 +202,7 @@ fn benchmark_nested_object_pretty(c: &mut Criterion) {
         json.push('}');
     }
 
-    bench_compare(c, "read-nested-object-pretty", json.as_str());
+    bench_compare(c, "read-nested-object-pretty", &json);
 }
 
 fn bench_compare_string_reading(c: &mut Criterion, name: &str, json: &str) {
@@ -212,7 +212,7 @@ fn bench_compare_string_reading(c: &mut Criterion, name: &str, json: &str) {
         b.iter(|| {
             call_unwrap(|| {
                 let mut json_reader = JsonStreamReader::new(json.as_bytes());
-                json_reader.next_string()?;
+                json_reader.next_str()?;
                 json_reader.consume_trailing_whitespace()?;
 
                 Ok(())
@@ -289,8 +289,8 @@ fn bench_compare_string_reading(c: &mut Criterion, name: &str, json: &str) {
 
 fn benchmark_large_ascii_string(c: &mut Criterion) {
     let json = "\"".to_owned() + "this is a test string".repeat(10_000).as_str() + "\"";
-    bench_compare(c, "read-large-ascii-string", json.as_str());
-    bench_compare_string_reading(c, "read-large-ascii-string (string reading)", json.as_str());
+    bench_compare(c, "read-large-ascii-string", &json);
+    bench_compare_string_reading(c, "read-large-ascii-string (string reading)", &json);
 }
 
 fn benchmark_large_unicode_string(c: &mut Criterion) {
@@ -299,12 +299,8 @@ fn benchmark_large_unicode_string(c: &mut Criterion) {
             .repeat(10_000)
             .as_str()
         + "\"";
-    bench_compare(c, "read-large-unicode-string", json.as_str());
-    bench_compare_string_reading(
-        c,
-        "read-large-unicode-string (string reading)",
-        json.as_str(),
-    );
+    bench_compare(c, "read-large-unicode-string", &json);
+    bench_compare_string_reading(c, "read-large-unicode-string (string reading)", &json);
 }
 
 fn benchmark_escapes_string(c: &mut Criterion) {
@@ -313,12 +309,8 @@ fn benchmark_escapes_string(c: &mut Criterion) {
             .repeat(10_000)
             .as_str()
         + "\"";
-    bench_compare(c, "read-large-escapes-string", json.as_str());
-    bench_compare_string_reading(
-        c,
-        "read-large-escapes-string (string reading)",
-        json.as_str(),
-    );
+    bench_compare(c, "read-large-escapes-string", &json);
+    bench_compare_string_reading(c, "read-large-escapes-string (string reading)", &json);
 }
 
 criterion_group!(

benches/reader_struct_benchmark.rs

@@ -22,9 +22,8 @@ fn benchmark_struct(c: &mut Criterion) {
 
     static COUNT: usize = 5000;
     let json = r#"{"bool_value": true, "integer": 123456, "float": 1234.56, "string": "this is a string value"}"#.repeat(COUNT);
-    let json = json.as_str();
 
-    group.bench_with_input("struson", json, |b, json| {
+    group.bench_with_input("struson", &json, |b, json| {
         b.iter(|| {
             let mut json_reader = JsonStreamReader::new_custom(
                 json.as_bytes(),
@@ -46,7 +45,7 @@ fn benchmark_struct(c: &mut Criterion) {
 
                     json_reader.begin_object()?;
                     while json_reader.has_next()? {
-                        match json_reader.next_name()?.as_str() {
+                        match json_reader.next_name()? {
                             "bool_value" => {
                                 bool_value = Some(json_reader.next_bool()?);
                             }

benches/writer_benchmark.rs

@@ -101,42 +101,43 @@ fn bench_compare_string_writing(c: &mut Criterion, name: &str, string_value: &st
 
 fn benchmark_large_ascii_string(c: &mut Criterion) {
     let string_value = "this is a test string".repeat(10_000);
-    let string_value = string_value.as_str();
     bench_compare(c, "write-large-ascii-string", |json_writer| {
-        json_writer.string_value(string_value)?;
+        json_writer.string_value(&string_value)?;
 
         Ok(())
     });
-    bench_compare_string_writing(c, "write-large-ascii-string (string writing)", string_value);
+    bench_compare_string_writing(
+        c,
+        "write-large-ascii-string (string writing)",
+        &string_value,
+    );
 }
 
 fn benchmark_large_unicode_string(c: &mut Criterion) {
     let string_value = "ab\u{0080}cd\u{0800}ef\u{1234}gh\u{10FFFF}".repeat(10_000);
-    let string_value = string_value.as_str();
     bench_compare(c, "write-large-unicode-string", |json_writer| {
-        json_writer.string_value(string_value)?;
+        json_writer.string_value(&string_value)?;
 
         Ok(())
     });
     bench_compare_string_writing(
         c,
         "write-large-unicode-string (string writing)",
-        string_value,
+        &string_value,
     );
 }
 
 fn benchmark_escapes_string(c: &mut Criterion) {
     let string_value = r#"a\nb\tc\\d\"e\u0000f\u0080g\u0800h\u1234i\uD800\uDC00"#.repeat(10_000);
-    let string_value = string_value.as_str();
     bench_compare(c, "write-large-escapes-string", |json_writer| {
-        json_writer.string_value(string_value)?;
+        json_writer.string_value(&string_value)?;
 
         Ok(())
     });
     bench_compare_string_writing(
         c,
         "write-large-escapes-string (string writing)",
-        string_value,
+        &string_value,
     );
 }
 

src/json_number.rs

@@ -1,11 +1,17 @@
 //! Internal module for parsing / validating JSON numbers
 
+pub(crate) trait NumberBytesProvider<E> {
+    /// Consumes the byte which is currently processed, and peeks at the next.
+    ///
+    /// Returns `None` if the end of the input has been reached.
+    fn consume_current_peek_next(&mut self) -> Result<Option<u8>, E>;
+}
+
 /// Returns `None` if the number is invalid and `Some(exponent_digits_count)` if
 /// the number is valid. The `exponent_digits_count` is the number of exponent
 /// digits, without sign and without leading 0s.
-pub fn consume_json_number<E, F: FnMut() -> Result<Option<u8>, E>, C: FnMut(u8)>(
-    consume_current_peek_next: &mut F,
-    consumer: &mut C,
+pub(crate) fn consume_json_number<E, R: NumberBytesProvider<E>>(
+    reader: &mut R,
     first_byte: u8,
 ) -> Result<Option<u32>, E> {
     #[derive(PartialEq)]
@@ -91,10 +97,8 @@ pub fn consume_json_number<E, F: FnMut() -> Result<Option<u8>, E>, C: FnMut(u8)>
             break;
         }
 
-        consumer(byte);
-
         // In the first iteration this consumes the `first_byte` argument
-        if let Some(peeked_byte) = consume_current_peek_next()? {
+        if let Some(peeked_byte) = reader.consume_current_peek_next()? {
             byte = peeked_byte;
         } else {
             has_trailing_number_chars = false;

src/lib.rs

@@ -51,7 +51,7 @@
 //! let mut json_reader = JsonStreamReader::new(json.as_bytes());
 //!
 //! json_reader.begin_object()?;
-//! assert_eq!(json_reader.next_name()?, "a");
+//! assert_eq!("a", json_reader.next_name()?);
 //!
 //! json_reader.begin_array()?;
 //! assert_eq!(1_u32, json_reader.next_number()??);