feat: Implement JSTable reading

Author: michaelmior

src/jstable.rs

@@ -0,0 +1,60 @@
+use crate::schema::Schema;
+use serde_json::Value;
+use std::collections::BTreeMap;
+use std::io::{self, BufReader, BufRead};
+use std::fs::File;
+
+pub struct JSTable {
+    pub schema: Schema,
+    pub documents: BTreeMap<String, Value>,
+}
+
+pub fn read_jstable(path: &str) -> io::Result<JSTable> {
+    let file = File::open(path)?;
+    let reader = BufReader::new(file);
+    let mut lines = reader.lines();
+
+    let schema_line = lines.next().ok_or_else(|| io::Error::new(io::ErrorKind::InvalidData, "Missing schema line"))??;
+    let schema: Schema = serde_json::from_str(&schema_line)?;
+
+    let mut documents = BTreeMap::new();
+    for line_result in lines {
+        let line = line_result?;
+        let record: (String, Value) = serde_json::from_str(&line)?;
+        documents.insert(record.0, record.1);
+    }
+
+    Ok(JSTable { schema, documents })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::schema::SchemaType;
+    use serde_json::json;
+    use tempfile::NamedTempFile;
+    use std::io::Write;
+
+    #[test]
+    fn test_read_jstable() -> Result<(), Box<dyn std::error::Error>> {
+        let mut file = NamedTempFile::new().unwrap();
+        let schema_json = serde_json::to_string(&Schema {
+            types: vec![SchemaType::Object],
+            properties: Some(BTreeMap::from([
+                ("a".to_string(), Schema::new(SchemaType::Integer)),
+            ])),
+            items: None,
+        }).unwrap();
+        writeln!(file, "{}", schema_json).unwrap();
+        writeln!(file, "{}", serde_json::to_string(&json!(["id1", {"a": 1}]))?).unwrap();
+        writeln!(file, "{}", serde_json::to_string(&json!(["id2", {"a": 2}]))?).unwrap();
+
+        let jstable = read_jstable(file.path().to_str().unwrap()).unwrap();
+
+        assert_eq!(jstable.schema.types, vec![SchemaType::Object]);
+        assert_eq!(jstable.documents.len(), 2);
+        assert_eq!(*jstable.documents.get("id1").unwrap(), json!({"a": 1}));
+        assert_eq!(*jstable.documents.get("id2").unwrap(), json!({"a": 2}));
+        Ok(())
+    }
+}

src/main.rs

@@ -2,6 +2,7 @@ pub mod schema;
 pub mod storage;
 pub mod log;
 pub mod db;
+pub mod jstable;
 
 fn main() {
     println!("Hello, world!");

src/schema.rs

@@ -25,7 +25,7 @@ pub struct Schema {
 }
 
 impl Schema {
-    fn new(schema_type: SchemaType) -> Self {
+    pub fn new(schema_type: SchemaType) -> Self {
         Schema {
             types: vec![schema_type],
             properties: None,