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// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! JSON Builders
//!
//! This module provides Builders that simplify constructing complex `Value`s. This can be useful
//! when dynamically constructing a `Value`, or when it is inconvenient to write a custom
//! `Serialize` implementation or to use `#[derive(Serialize)]`.
//!
//! # Example
//!
//! ```rust
//! use serde_json::builder::ObjectBuilder;
//!
//! let value = ObjectBuilder::new()
//!     .insert("name", "point")
//!     .insert_array("points", |builder| {
//!         builder
//!             .push_object(|builder| {
//!                 builder.insert("x", 1).insert("y", 2)
//!             })
//!             .push_object(|builder| {
//!                 builder.insert("x", 3).insert("y", 4)
//!             })
//!     })
//!     .unwrap();
//! ```

use std::collections::BTreeMap;

use serde::ser;

use value::{self, Value};

/// This structure provides a simple interface for constructing a JSON array.
pub struct ArrayBuilder {
    array: Vec<Value>,
}

impl ArrayBuilder {
    /// Construct an `ObjectBuilder`.
    pub fn new() -> ArrayBuilder {
        ArrayBuilder { array: Vec::new() }
    }

    /// Return the constructed `Value`.
    pub fn unwrap(self) -> Value {
        Value::Array(self.array)
    }

    /// Insert a value into the array.
    pub fn push<T: ser::Serialize>(mut self, v: T) -> ArrayBuilder {
        self.array.push(value::to_value(&v));
        self
    }

    /// Creates and passes an `ArrayBuilder` into a closure, then inserts the resulting array into
    /// this array.
    pub fn push_array<F>(mut self, f: F) -> ArrayBuilder where
        F: FnOnce(ArrayBuilder) -> ArrayBuilder
    {
        let builder = ArrayBuilder::new();
        self.array.push(f(builder).unwrap());
        self
    }

    /// Creates and passes an `ArrayBuilder` into a closure, then inserts the resulting object into
    /// this array.
    pub fn push_object<F>(mut self, f: F) -> ArrayBuilder where
        F: FnOnce(ObjectBuilder) -> ObjectBuilder
    {
        let builder = ObjectBuilder::new();
        self.array.push(f(builder).unwrap());
        self
    }
}

/// This structure provides a simple interface for constructing a JSON object.
pub struct ObjectBuilder {
    object: BTreeMap<String, Value>,
}

impl ObjectBuilder {
    /// Construct an `ObjectBuilder`.
    pub fn new() -> ObjectBuilder {
        ObjectBuilder { object: BTreeMap::new() }
    }

    /// Return the constructed `Value`.
    pub fn unwrap(self) -> Value {
        Value::Object(self.object)
    }

    /// Insert a key-value pair into the object.
    pub fn insert<S, V>(mut self, key: S, value: V) -> ObjectBuilder
        where S: Into<String>,
              V: ser::Serialize,
    {
        self.object.insert(key.into(), value::to_value(&value));
        self
    }

    /// Creates and passes an `ObjectBuilder` into a closure, then inserts the resulting array into
    /// this object.
    pub fn insert_array<S, F>(mut self, key: S, f: F) -> ObjectBuilder
        where S: Into<String>,
              F: FnOnce(ArrayBuilder) -> ArrayBuilder
    {
        let builder = ArrayBuilder::new();
        self.object.insert(key.into(), f(builder).unwrap());
        self
    }

    /// Creates and passes an `ObjectBuilder` into a closure, then inserts the resulting object into
    /// this object.
    pub fn insert_object<S, F>(mut self, key: S, f: F) -> ObjectBuilder
        where S: Into<String>,
              F: FnOnce(ObjectBuilder) -> ObjectBuilder
    {
        let builder = ObjectBuilder::new();
        self.object.insert(key.into(), f(builder).unwrap());
        self
    }
}