feat(ser): add wof serializer

Trying to implement whosonfirst/whosonfirst-cookbook#35

Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "wof-cli"
+name = "wof"
 version = "0.1.0"
 authors = ["Jones Magloire @Joxit"]
 description = "The Who's On First command line aggregator."
@@ -14,7 +14,7 @@ path = "src/main.rs"
 [dependencies]
 structopt = "0.3"
 which = "3.1.0"
-serde_json = "1.0"
+json = { git = "https://github.com/Joxit/json-rust.git", branch = "feat/custom-generator" }
 tar = "0.4.26"
 flate2 = "1.0.13"
 attohttpc = "0.8.0"

src/lib.rs

@@ -0,0 +1 @@
+pub mod ser;

src/main.rs

@@ -4,6 +4,7 @@ use structopt::StructOpt;
 
 mod commands;
 mod git;
+mod ser;
 mod std;
 
 #[derive(Debug, StructOpt)]

src/ser.rs

@@ -0,0 +1,153 @@
+use json::codegen::Generator;
+use json::object::Object;
+use json::JsonValue;
+use std::io::{self, Write};
+
+pub struct WOFGenerator<'a, W> {
+  writer: &'a mut W,
+  dent: u16,
+}
+
+impl<'a, W> WOFGenerator<'a, W>
+where
+  W: Write,
+{
+  pub fn new(writer: &'a mut W) -> WOFGenerator<W> {
+    WOFGenerator {
+      writer: writer,
+      dent: 0,
+    }
+  }
+
+  pub fn write_object_value_by_key(&mut self, key: &str, value: &JsonValue) -> io::Result<()> {
+    match key {
+      "bbox" => {
+        if let JsonValue::Array(ref array) = value {
+          self.write_char(b'[')?;
+          let mut iter = array.iter();
+
+          if let Some(item) = iter.next() {
+            self.indent();
+            self.new_line()?;
+            self.write_json(item)?;
+          } else {
+            self.write_char(b']')?;
+            return Ok(());
+          }
+
+          for item in iter {
+            self.write_char(b',')?;
+            self.new_line()?;
+            self.write_json(item)?;
+          }
+
+          self.dedent();
+          self.write_char(b'\n')?;
+          self.write_char(b']')
+        } else {
+          self.write_json(value)
+        }
+      }
+      "geometry" => value.write(&mut self.writer),
+      _ => self.write_json(value),
+    }
+  }
+}
+
+impl<'a, W> Generator for WOFGenerator<'a, W>
+where
+  W: Write,
+{
+  type T = W;
+
+  #[inline(always)]
+  fn get_writer(&mut self) -> &mut W {
+    &mut self.writer
+  }
+
+  #[inline(always)]
+  fn write_min(&mut self, colon_space: &[u8], colon: u8) -> io::Result<()> {
+    if self.dent == 1 {
+      self.writer.write_all(colon_space)
+    } else {
+      self.writer.write_all(&[colon])
+    }
+  }
+
+  #[inline(always)]
+  fn write_object(&mut self, object: &Object) -> io::Result<()> {
+    self.write_char(b'{')?;
+    let mut entries: Vec<(&str, &JsonValue)> = Vec::new();
+    for (k, v) in object.iter() {
+      entries.push((k, v));
+    }
+    if self.dent == 0 {
+      entries.sort_by(wof_first_level_ordering);
+    } else {
+      entries.sort_by(|(k1, _), (k2, _)| k1.partial_cmp(k2).unwrap());
+    }
+    let mut iter = entries.iter();
+    if let Some((key, value)) = iter.next() {
+      self.indent();
+      self.new_line()?;
+      self.write_string(key)?;
+      self.write_min(b": ", b':')?;
+      self.write_object_value_by_key(key, value)?;
+    } else {
+      self.write_char(b'}')?;
+      return Ok(());
+    }
+
+    for (key, value) in iter {
+      self.write_char(b',')?;
+      self.new_line()?;
+      self.write_string(key)?;
+      self.write_min(b": ", b':')?;
+      self.write_object_value_by_key(key, value)?;
+    }
+
+    self.dedent();
+    self.new_line()?;
+    self.write_char(b'}')
+  }
+
+  fn indent(&mut self) {
+    self.dent += 1;
+  }
+
+  fn dedent(&mut self) {
+    self.dent -= 1;
+  }
+
+  fn new_line(&mut self) -> io::Result<()> {
+    self.write_char(b'\n')?;
+    for _ in 0..(self.dent * 2) {
+      self.write_char(b' ')?;
+    }
+    Ok(())
+  }
+}
+
+fn wof_first_level_classify(key: &str) -> i32 {
+  match key {
+    "id" => 0,
+    "type" => 1,
+    "properties" => 2,
+    "bbox" => 4,
+    "geometry" => 5,
+    _ => 3,
+  }
+}
+
+fn wof_first_level_ordering(
+  (k1, _): &(&str, &JsonValue),
+  (k2, _): &(&str, &JsonValue),
+) -> std::cmp::Ordering {
+  if wof_first_level_classify(k1) < wof_first_level_classify(k2) {
+    std::cmp::Ordering::Less
+  } else if wof_first_level_classify(k1) > wof_first_level_classify(k2) {
+    std::cmp::Ordering::Greater
+  } else {
+    k1.partial_cmp(k2).unwrap()
+  }
+}

tests/test.rs

@@ -0,0 +1,93 @@
+#[macro_use]
+extern crate json;
+
+use json::codegen::Generator;
+use json::Null;
+use wof::ser::WOFGenerator;
+
+#[test]
+pub fn serialize_first_level_wof_geojson_with_null() {
+  let t = object! {
+    "type"=> Null,
+    "properties"=> Null,
+    "geometry"=> Null,
+    "bbox"=> Null,
+    "id"=> Null,
+  };
+  let mut vec: Vec<u8> = Vec::new();
+  assert!(WOFGenerator::new(&mut vec).write_json(&t).is_ok());
+  assert_eq!(
+    String::from_utf8(vec).unwrap(),
+    r#"{
+  "id": null,
+  "type": null,
+  "properties": null,
+  "bbox": null,
+  "geometry": null
+}"#
+  );
+}
+
+#[test]
+pub fn serialize_first_level_wof_geojson_with_content() {
+  let t = object! {
+    "type"=>"Feature",
+    "properties"=> object!{
+      "name:fra_x_preferred" => vec![
+        "Ajaccio"
+      ],
+      "wof:id"=>101748927,
+      "wof:lang" => vec![
+        "fre"
+      ],
+      "name:eng_x_preferred" => vec![
+        "Ajaccio"
+      ],
+    },
+    "geometry"=> object!{
+      "coordinates" => vec![vec![
+        vec![8.585396,41.873571],
+        vec![8.826011,41.873571],
+        vec![8.826011,41.971536],
+        vec![8.585396,41.968222],
+        vec![8.585396,41.873571]
+      ]],
+      "type" => "Polygon"
+    },
+    "bbox"=> vec![
+      8.585396,
+      41.873571,
+      8.826011,
+      41.971536
+    ],
+    "id"=> 101748927,
+  };
+  let mut vec: Vec<u8> = Vec::new();
+  assert!(WOFGenerator::new(&mut vec).write_json(&t).is_ok());
+  assert_eq!(
+    String::from_utf8(vec).unwrap(),
+    r#"{
+  "id": 101748927,
+  "type": "Feature",
+  "properties": {
+    "name:eng_x_preferred":[
+      "Ajaccio"
+    ],
+    "name:fra_x_preferred":[
+      "Ajaccio"
+    ],
+    "wof:id":101748927,
+    "wof:lang":[
+      "fre"
+    ]
+  },
+  "bbox": [
+    8.585396,
+    41.873571,
+    8.826011,
+    41.971536
+],
+  "geometry": {"coordinates":[[[8.585396,41.873571],[8.826011,41.873571],[8.826011,41.971536],[8.585396,41.968222],[8.585396,41.873571]]],"type":"Polygon"}
+}"#
+  );
+}