initial working java codegen prototype

Author: zahash

.gitignore

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+/target
+sample.json

Cargo.lock

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+[package]
+name = "jsoncodegen"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+clap = { version = "4", features = ["derive"] }
+anyhow = "1"

Cargo.toml

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+use crate::schema_extraction::{FieldType, Structure};
+use std::io::{Error, Write};
+
+pub fn java<W: Write>(schema: &[Structure], out: &mut W) -> Result<(), Error> {
+    for class in schema {
+        writeln!(out, "class {} {{", class.name)?;
+
+        for field in &class.fields {
+            let java_type = field_type_to_java_type(&field.type_);
+            writeln!(out, "    {} {};", java_type, field.name)?;
+        }
+
+        writeln!(out, "}}")?;
+    }
+
+    Ok(())
+}
+
+fn field_type_to_java_type(field_type: &FieldType) -> String {
+    match field_type {
+        FieldType::String => "String".into(),
+        FieldType::Integer => "Integer".into(),
+        FieldType::Float => "Double".into(),
+        FieldType::Boolean => "Boolean".into(),
+        FieldType::Unknown => "Object".into(),
+        FieldType::Object(name) => name.into(),
+        FieldType::Array(type_) => format!("List<{}>", field_type_to_java_type(type_)),
+    }
+}

src/codegen/java.rs

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+mod java;
+
+pub use java::java;

src/codegen/mod.rs

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+use std::{fs::File, io::BufReader};
+
+use clap::Parser;
+use serde_json::Value;
+
+mod codegen;
+mod schema_extraction;
+
+#[derive(Parser, Debug)]
+struct JSONCodeGen {
+    /// json filepath
+    #[arg(short, long)]
+    filepath: String,
+}
+
+fn main() -> anyhow::Result<()> {
+    let args = JSONCodeGen::parse();
+
+    let file = File::open(args.filepath)?;
+    let reader = BufReader::new(file);
+
+    let json: Value = serde_json::from_reader(reader)?;
+    let schema = schema_extraction::process(json);
+    let mut stdout = std::io::stdout().lock();
+    codegen::java(&schema, &mut stdout)?;
+
+    Ok(())
+}