Remove serde (#23)

generator/Cargo.toml

@@ -10,6 +10,5 @@ edition = "2021"
 clap = { version = "4.3.1", features = [ "derive" ] }
 rand = "0.8.5"
 haversine = { path = "../haversine" }
-serde_json = "1.0.96"
-serde = "1.0.163"
+json = { path = "../json" }
 byteorder = "1.4.3"

generator/src/main.rs

@@ -1,7 +1,8 @@
-use byteorder::{ByteOrder, LittleEndian};
+use byteorder::{BigEndian, ByteOrder};
 use clap::{builder::PossibleValue, Parser, ValueEnum};
 use haversine::haversine::{CoordinatePair, HaversineData};
 use haversine::{distance, earth};
+use json::json_object::JsonValue;
 use rand::distributions::Distribution;
 use rand::rngs::StdRng;
 use rand::{Rng, SeedableRng};
@@ -63,10 +64,41 @@ fn write_json(data: &HaversineData, json_filename: &str) {
     let output_file = File::create(json_filename).unwrap();
     let mut writer = BufWriter::new(output_file);
 
-    serde_json::to_writer(&mut writer, &data).unwrap();
+    writer.write_all(r#"{"pairs":["#.as_bytes()).unwrap();
+
+    let mut is_first = true;
+    for point in data.pairs.iter() {
+        if !is_first {
+            writer.write_all(&[b',']).unwrap();
+        }
+        writer.write_all(&[b'{']).unwrap();
+        writer
+            .write_all(
+                format!(
+                    r#""x0":{:.17},"y0":{:.17},"x1":{:.17},"y1":{:.17}"#,
+                    point.x0, point.y0, point.x1, point.y1
+                )
+                .as_bytes(),
+            )
+            .unwrap();
+        writer.write_all(&[b'}']).unwrap();
+        is_first = false;
+    }
+
+    writer.write_all("]}".as_bytes()).unwrap();
     writer.flush().unwrap();
 }
 
+// Our JSON parser is incapable of round-tripping floats, for precision reasons.
+// To work around this, we'll just compute using the serialised versions.
+fn round_trip_float(f: f64) -> f64 {
+    let written = format!("{:.17}", f);
+    JsonValue::parse(&mut written.chars())
+        .unwrap()
+        .0
+        .as_number()
+}
+
 fn write_answer(data: &HaversineData, binary_filename: &str) {
     let output_file = File::create(binary_filename).unwrap();
     let mut writer = BufWriter::new(output_file);
@@ -75,8 +107,15 @@ fn write_answer(data: &HaversineData, binary_filename: &str) {
 
     let mut buf = [0u8; 8];
     for (count, point) in data.pairs.iter().enumerate() {
-        let distance = distance::naive(point, earth::RADIUS);
-        LittleEndian::write_f64(&mut buf, distance);
+        let point = CoordinatePair {
+            x0: round_trip_float(point.x0),
+            y0: round_trip_float(point.y0),
+            x1: round_trip_float(point.x1),
+            y1: round_trip_float(point.y1),
+        };
+
+        let distance = distance::naive(&point, earth::RADIUS);
+        BigEndian::write_f64(&mut buf, distance);
 
         let written = writer.write(&buf).unwrap();
         if written < buf.len() {
@@ -90,7 +129,7 @@ fn write_answer(data: &HaversineData, binary_filename: &str) {
     // sic!
     println!("Expected sum: {}", expected_average);
 
-    LittleEndian::write_f64(&mut buf, expected_average);
+    BigEndian::write_f64(&mut buf, expected_average);
     let written = writer.write(&buf).unwrap();
     if written < buf.len() {
         panic!("Failed to write everything")