vdf_serde_format/

serializer.rs

use serde::{
    ser::{self, SerializeSeq},
    Serialize,
};

use crate::{
    error::{Error, Result},
    peek_expect_char, preprocess,
    preprocessor::parse_string,
};

#[derive(Clone, Copy, PartialEq, PartialOrd, Debug)]
#[allow(dead_code)]
enum LogLevel {
    Error = 0,
    Warn = 1,
    Info = 2,
    Debug = 3,
    Trace = 4,
}

#[cfg(debug_assertions)]
static mut INDENTATION: usize = 0;

#[cfg(debug_assertions)]
static mut CURRENT_LEVEL: LogLevel = LogLevel::Debug;
macro_rules! log {
    ($level:expr, $($arg:tt)*) => ({
        #[cfg(debug_assertions)]
        {
            let current_level = unsafe { CURRENT_LEVEL };
            if $level <= current_level {
                let indentation = unsafe { "\t".repeat(INDENTATION) };
                println!("{}{}", indentation, format!($($arg)*));
            }
        }
    });
}

pub struct Serializer {
    // This string starts empty and JSON is appended as values are serialized.
    output: String,
    indentation: usize,
    array_key: Option<String>,
}

// By convention, the public API of a Serde serializer is one or more `to_abc`
// functions such as `to_string`, `to_bytes`, or `to_writer` depending on what
// Rust types the serializer is able to produce as output.
//
// This basic serializer supports only `to_string`.
pub fn to_string<T>(value: &T) -> Result<String>
where
    T: Serialize,
{
    let mut serializer = Serializer {
        output: String::new(),
        indentation: 0,
        array_key: None,
    };
    value.serialize(&mut serializer)?;

    log!(
        LogLevel::Debug,
        "Serializer Output:\n{:?}",
        serializer.output
    );

    {
        let mut temp_output = serializer.output.clone();

        // Run a preprocessor over the serialized output.
        if peek_expect_char(&serializer.output, 0, '"').unwrap_or(false) {
            let header = parse_string(&temp_output)?;
            temp_output = header.1.to_string();

            if peek_expect_char(&temp_output, 0, '{').unwrap_or(false) {
                log!(LogLevel::Debug, "Preprocessing serializer...");
                serializer.output = preprocess(&serializer.output, true, true).unwrap();
            }
        }
    }

    Ok(serializer.output)
}

impl<'a> ser::Serializer for &'a mut Serializer {
    // The output type produced by this `Serializer` during successful
    // serialization. Most serializers that produce text or binary output should
    // set `Ok = ()` and serialize into an `io::Write` or buffer contained
    // within the `Serializer` instance, as happens here. Serializers that build
    // in-memory data structures may be simplified by using `Ok` to propagate
    // the data structure around.
    type Ok = ();

    // The error type when some error occurs during serialization.
    type Error = Error;

    // Associated types for keeping track of additional state while serializing
    // compound data structures like sequences and maps. In this case no
    // additional state is required beyond what is already stored in the
    // Serializer struct.
    type SerializeSeq = Self;
    type SerializeTuple = Self;
    type SerializeTupleStruct = Self;
    type SerializeTupleVariant = Self;
    type SerializeMap = Self;
    type SerializeStruct = Self;
    type SerializeStructVariant = Self;

    // Here we go with the simple methods. The following 12 methods receive one
    // of the primitive types of the data model and map it to JSON by appending
    // into the output string.
    fn serialize_bool(self, v: bool) -> Result<()> {
        self.output += if v { "\"1\"" } else { "\"0\"" };
        Ok(())
    }

    // JSON does not distinguish between different sizes of integers, so all
    // signed integers will be serialized the same and all unsigned integers
    // will be serialized the same. Other formats, especially compact binary
    // formats, may need independent logic for the different sizes.
    fn serialize_i8(self, v: i8) -> Result<()> {
        self.serialize_i64(i64::from(v))
    }

    fn serialize_i16(self, v: i16) -> Result<()> {
        self.serialize_i64(i64::from(v))
    }

    fn serialize_i32(self, v: i32) -> Result<()> {
        self.serialize_i64(i64::from(v))
    }

    // Not particularly efficient but this is example code anyway. A more
    // performant approach would be to use the `itoa` crate.
    fn serialize_i64(self, v: i64) -> Result<()> {
        self.output += &format!("\"{}\"", v).to_string();
        Ok(())
    }

    fn serialize_u8(self, v: u8) -> Result<()> {
        self.serialize_u64(u64::from(v))
    }

    fn serialize_u16(self, v: u16) -> Result<()> {
        self.serialize_u64(u64::from(v))
    }

    fn serialize_u32(self, v: u32) -> Result<()> {
        self.serialize_u64(u64::from(v))
    }

    fn serialize_u64(self, v: u64) -> Result<()> {
        self.output += &format!("\"{}\"", v).to_string();
        Ok(())
    }

    fn serialize_f32(self, v: f32) -> Result<()> {
        self.serialize_f64(f64::from(v))
    }

    fn serialize_f64(self, v: f64) -> Result<()> {
        self.output += &format!("\"{}\"", v).to_string();
        Ok(())
    }

    // Serialize a char as a single-character string. Other formats may
    // represent this differently.
    fn serialize_char(self, v: char) -> Result<()> {
        self.serialize_str(&v.to_string())
    }

    // This only works for strings that don't require escape sequences but you
    // get the idea. For example it would emit invalid JSON if the input string
    // contains a '"' character.
    fn serialize_str(self, v: &str) -> Result<()> {
        self.output += &format!("\"{}\"", v).to_string();
        self.array_key = Some(v.to_string());
        Ok(())
    }

    // Serialize a byte array as an array of bytes. Could also use a base64
    // string here. Binary formats will typically represent byte arrays more
    // compactly.
    fn serialize_bytes(self, v: &[u8]) -> Result<()> {
        use serde::ser::SerializeSeq;
        let mut seq = self.serialize_seq(Some(v.len()))?;
        for byte in v {
            seq.serialize_element(byte)?;
        }
        seq.end()
    }

    // An absent optional is represented as the JSON `null`.
    fn serialize_none(self) -> Result<()> {
        self.serialize_unit()
    }

    // A present optional is represented as just the contained value. Note that
    // this is a lossy representation. For example the values `Some(())` and
    // `None` both serialize as just `null`. Unfortunately this is typically
    // what people expect when working with JSON. Other formats are encouraged
    // to behave more intelligently if possible.
    fn serialize_some<T>(self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    // In Serde, unit means an anonymous value containing no data. Map this to
    // JSON as `null`.
    fn serialize_unit(self) -> Result<()> {
        self.output += "null";
        Ok(())
    }

    // Unit struct means a named value containing no data. Again, since there is
    // no data, map this to JSON as `null`. There is no need to serialize the
    // name in most formats.
    fn serialize_unit_struct(self, _name: &'static str) -> Result<()> {
        self.serialize_unit()
    }

    // When serializing a unit variant (or any other kind of variant), formats
    // can choose whether to keep track of it by index or by name. Binary
    // formats typically use the index of the variant and human-readable formats
    // typically use the name.
    fn serialize_unit_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        variant: &'static str,
    ) -> Result<()> {
        self.serialize_str(variant)
    }

    // As is done here, serializers are encouraged to treat newtype structs as
    // insignificant wrappers around the data they contain.
    fn serialize_newtype_struct<T>(self, _name: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(self)
    }

    // Note that newtype variant (and all of the other variant serialization
    // methods) refer exclusively to the "externally tagged" enum
    // representation.
    //
    // Serialize this to JSON in externally tagged form as `{ NAME: VALUE }`.
    fn serialize_newtype_variant<T>(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        value: &T,
    ) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        value.serialize(&mut *self)?;
        Ok(())
    }

    // Now we get to the serialization of compound types.
    //
    // The start of the sequence, each value, and the end are three separate
    // method calls. This one is responsible only for serializing the start,
    // which in JSON is `[`.
    //
    // The length of the sequence may or may not be known ahead of time. This
    // doesn't make a difference in JSON because the length is not represented
    // explicitly in the serialized form. Some serializers may only be able to
    // support sequences for which the length is known up front.
    fn serialize_seq(self, _len: Option<usize>) -> Result<Self::SerializeSeq> {
        // Delete the last key, since we are about to serialize a sequence.
        // let key = self.array_key.clone().unwrap();
        // let loc = self.output.rfind(format!("\"{}\"", key).as_str()).unwrap();
        // self.output = self.output[..loc].to_string();
        Ok(self)
    }

    fn collect_seq<I>(self, iter: I) -> std::result::Result<Self::Ok, Self::Error>
    where
        I: IntoIterator,
        <I as IntoIterator>::Item: Serialize,
    {
        if self.array_key.is_none() {
            panic!("Expected a key before a sequence.");
        }

        let key = self.array_key.clone().unwrap();

        // Delete the last key, since we are about to serialize a sequence.
        let loc = self
            .output
            .rfind(format!("\n{}\"{}\"\t\t", "\t".repeat(self.indentation), key).as_str())
            .unwrap();
        self.output = self.output[..loc].to_string();

        let seq = self.serialize_seq(None)?;
        for value in iter {
            // Skip the first element, since it is the key.
            let ends_with_key = seq.output.ends_with(key.as_str());
            if !ends_with_key {
                seq.output += "\n";
                seq.output += "\t".repeat(seq.indentation).as_str();
                // seq.output += "sek";
                key.serialize(&mut *seq)?;
            }
            seq.output += "\t\t";
            // seq.output += "sev";
            value.serialize(&mut *seq)?;
        }
        seq.end()?;
        self.array_key = None;
        Ok(())
    }

    // Tuples look just like sequences in JSON. Some formats may be able to
    // represent tuples more efficiently by omitting the length, since tuple
    // means that the corresponding `Deserialize implementation will know the
    // length without needing to look at the serialized data.
    fn serialize_tuple(self, _len: usize) -> Result<Self::SerializeTuple> {
        Ok(self)
    }

    // Tuple structs look just like sequences in JSON.
    fn serialize_tuple_struct(
        self,
        _name: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleStruct> {
        Ok(self)
    }

    // Tuple variants are represented in JSON as `{ NAME: [DATA...] }`. Again
    // this method is only responsible for the externally tagged representation.
    fn serialize_tuple_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeTupleVariant> {
        Ok(self)
    }

    // Maps are represented in JSON as `{ K: V, K: V, ... }`.
    fn serialize_map(self, _len: Option<usize>) -> Result<Self::SerializeMap> {
        if self.output.len() > 0 {
            self.output += "\n";
            self.output += "\t".repeat(self.indentation).as_str();
            self.output += "{\n";
            self.indentation += 1;
        }
        Ok(self)
    }

    // Structs look just like maps in JSON. In particular, JSON requires that we
    // serialize the field names of the struct. Other formats may be able to
    // omit the field names when serializing structs because the corresponding
    // Deserialize implementation is required to know what the keys are without
    // looking at the serialized data.
    fn serialize_struct(self, _name: &'static str, len: usize) -> Result<Self::SerializeStruct> {
        // if self.output.len() == 0 {
        //     self.output += " ";
        // }

        self.serialize_map(Some(len))
    }

    // Struct variants are represented in JSON as `{ NAME: { K: V, ... } }`.
    // This is the externally tagged representation.
    fn serialize_struct_variant(
        self,
        _name: &'static str,
        _variant_index: u32,
        _variant: &'static str,
        _len: usize,
    ) -> Result<Self::SerializeStructVariant> {
        self.output += "\n";
        self.output += "\t".repeat(self.indentation).as_str();
        self.output += "{\n";
        self.indentation += 1;
        Ok(self)
    }
}

// The following 7 impls deal with the serialization of compound types like
// sequences and maps. Serialization of such types is begun by a Serializer
// method and followed by zero or more calls to serialize individual elements of
// the compound type and one call to end the compound type.
//
// This impl is SerializeSeq so these methods are called after `serialize_seq`
// is called on the Serializer.
impl<'a> ser::SerializeSeq for &'a mut Serializer {
    // Must match the `Ok` type of the serializer.
    type Ok = ();
    // Must match the `Error` type of the serializer.
    type Error = Error;

    // Serialize a single element of the sequence.
    fn serialize_element<T>(&mut self, _value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        Ok(())
    }

    // Close the sequence.
    fn end(self) -> Result<()> {
        self.output = self.output.trim().to_string();
        Ok(())
    }
}

// Some `Serialize` types are not able to hold a key and value in memory at the
// same time so `SerializeMap` implementations are required to support
// `serialize_key` and `serialize_value` individually.
//
// There is a third optional method on the `SerializeMap` trait. The
// `serialize_entry` method allows serializers to optimize for the case where
// key and value are both available simultaneously.
impl<'a> ser::SerializeMap for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_key<T>(&mut self, key: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.output += "\n";
        self.output += "\t".repeat(self.indentation).as_str();
        key.serialize(&mut **self)
    }

    // It doesn't make a difference whether the colon is printed at the end of
    // `serialize_key` or at the beginning of `serialize_value`. In this case
    // the code is a bit simpler having it here.
    fn serialize_value<T>(&mut self, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.output += "\t\t";
        value.serialize(&mut **self)
    }

    fn end(self) -> Result<()> {
        if self.indentation > 0 {
            self.indentation -= 1;
            self.output += "\n";
            self.output += "\t".repeat(self.indentation).as_str();
            self.output += "}";
        }
        Ok(())
    }
}

// Structs are like maps in which the keys are constrained to be compile-time
// constant strings.
impl<'a> ser::SerializeStruct for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.output += "\t".repeat(self.indentation).as_str();
        key.serialize(&mut **self)?;
        self.output += "\t\t";
        let result = value.serialize(&mut **self);
        self.output += "\n";
        result
    }

    fn end(self) -> Result<()> {
        if self.indentation > 0 {
            self.indentation -= 1;
            self.output += "\n";
            self.output += "\t".repeat(self.indentation).as_str();
            self.output += "}";
        }
        Ok(())
    }
}

// Similar to `SerializeTupleVariant`, here the `end` method is responsible for
// closing both of the curly braces opened by `serialize_struct_variant`.
impl<'a> ser::SerializeStructVariant for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, key: &'static str, value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        self.output += "\t".repeat(self.indentation).as_str();
        key.serialize(&mut **self)?;
        self.output += "\t\t";
        let result = value.serialize(&mut **self);
        self.output += "\n";
        result
    }

    fn end(self) -> Result<()> {
        self.indentation -= 1;
        self.output += "\t".repeat(self.indentation).as_str();
        self.output += "}";
        Ok(())
    }
}

// Tuple Structs aren't supported, because they don't have keys of the fields.
// So we cannot map them, as in VDF format is built on mappable sequences.
impl<'a> ser::SerializeTupleStruct for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, _value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        Err(Error::CannotSupportedTupleType)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

// Tuple Variants aren't supported, because they don't have keys of the fields.
// So we cannot map them, as in VDF format is built on mappable sequences.
impl<'a> ser::SerializeTupleVariant for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_field<T>(&mut self, _value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        Err(Error::CannotSupportedTupleType)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}
// Plain Tuple aren't supported, because they don't have keys of the fields.
// So we cannot map them, as in VDF format is built on mappable sequences.
impl<'a> ser::SerializeTuple for &'a mut Serializer {
    type Ok = ();
    type Error = Error;

    fn serialize_element<T>(&mut self, _value: &T) -> Result<()>
    where
        T: ?Sized + Serialize,
    {
        Err(Error::CannotSupportedTupleType)
    }

    fn end(self) -> Result<()> {
        Ok(())
    }
}

////////////////////////////////////////////////////////////////////////////////
#[cfg(test)]
mod tests {
    use super::*;

    mod enums {
        use super::*;

        #[derive(Serialize)]
        struct TestTupleStruct(u32, u32);

        #[derive(Serialize)]
        enum Test {
            A(String),            // This will succeed. Enum Variant Primitives are supported.
            B(bool),              // This will succeed. Enum Variant Primitives are supported.
            C { x: i32, y: i32 }, // This will succeed. Enum Variant Struct are supported.
            D((i32, i32)),        // This will fail.  Enum Tuple are not supported.
            E(String, i32),       // This will fail.  Enum Tuple Variant are not supported.
            F(TestTupleStruct),   // This will fail.  Enum Struct Tuple structs are not supported.
        }
        #[derive(Serialize)]
        struct TestContainer {
            test: Test,
        }

        #[test]
        fn supported_enum_variant_string() {
            log!(LogLevel::Debug, "Test A(String) - Enum Variant / Primitive");
            let result = TestContainer {
                test: Test::A("Hello World!".to_string()),
            };

            let expected = r#"
                "test"        "Hello World!"
            "#;
            let result_str = to_string(&result).unwrap();
            log!(LogLevel::Debug, "Result:\n{}", result_str);

            // Remove all whitespace for assertion test.
            let result_str = result_str.replace(|c: char| c.is_whitespace(), "");
            let expected_str = expected.replace(|c: char| c.is_whitespace(), "");
            assert_eq!(result_str, expected_str);
        }

        #[test]
        fn supported_enum_variant_bool() {
            log!(LogLevel::Debug, "Test B(bool) - Enum Variant / Primitive");
            let result = TestContainer {
                test: Test::B(true),
            };

            let expected = r#"
                "test"        "1"
            "#;
            let result_str = to_string(&result).unwrap();
            log!(LogLevel::Debug, "Result:\n{}", result_str);

            // Remove all whitespace for assertion test.
            let result_str = result_str.replace(|c: char| c.is_whitespace(), "");
            let expected_str = expected.replace(|c: char| c.is_whitespace(), "");
            assert_eq!(result_str, expected_str);
        }

        #[test]
        fn supported_enum_variant_struct() {
            log!(
                LogLevel::Debug,
                "Test C {{ x: i32, y: i32 }} - Enum Variant / Struct"
            );
            let result = TestContainer {
                test: Test::C { x: 1, y: 2 },
            };

            let expected = r#"
                "test"        
                {
                    "x"      "1"
                    "y"      "2"
                }
            "#;
            let result_str = to_string(&result).unwrap();
            log!(LogLevel::Debug, "Result:\n{}", result_str);

            // Remove all whitespace for assertion test.
            let result_str = result_str.replace(|c: char| c.is_whitespace(), "");
            let expected_str = expected.replace(|c: char| c.is_whitespace(), "");
            assert_eq!(result_str, expected_str);
        }

        #[test]
        fn unsupported_tuple_variant_enum() {
            log!(
                LogLevel::Debug,
                "Test D((i32, i32)) - Tuple Variant Enum - Expected to Fail, unsupported tuple type"
            );
            let result = TestContainer {
                test: Test::D((1, 2)),
            };
            let result = to_string(&result).is_err();
            assert!(result);
        }

        #[test]
        fn unsupported_enum_tuple_variant() {
            log!(
                LogLevel::Debug,
                "Test E(String, i32) - Enum Tuple Variant - Expected to Fail, unsupported tuple type"
            );
            let result = TestContainer {
                test: Test::E("Hello World!".to_string(), 1),
            };

            let result = to_string(&result).is_err();
            assert!(result);
        }

        #[test]
        fn unsupported_enum_tuple_struct() {
            log!(
                LogLevel::Debug,
                "Test F(TestTupleStruct) - Tuple Struct - Expected to Fail, unsupported tuple type"
            );
            let result = TestContainer {
                test: Test::F(TestTupleStruct(1, 2)),
            };

            let result = to_string(&result).is_err();
            assert!(result);
        }
    }

    mod primitives {
        use super::*;

        #[test]
        fn supported_strs() {
            let result = "Hello World!";
            let expected = r#""Hello World!""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_bool_true() {
            let result = true;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_bool_false() {
            let result = false;
            let expected = r#""0""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_i8() {
            let result = 1i8;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_i16() {
            let result = 1i16;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_i32() {
            let result = 1i32;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_i64() {
            let result = 1i64;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_u8() {
            let result = 1u8;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_u16() {
            let result = 1u16;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_u32() {
            let result = 1u32;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_u64() {
            let result = 1u64;
            let expected = r#""1""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_f32() {
            let result = 0.25f32;
            let expected = r#""0.25""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }

        #[test]
        fn supported_f64() {
            let result = 0.45f64;
            let expected = r#""0.45""#;
            let result_str = to_string(&result).unwrap();
            assert_eq!(result_str, expected);
        }
    }

    mod structs {
        use super::*;

        #[derive(Serialize)]
        struct Test {
            int: u32,
            seq: Vec<&'static str>,
        }

        #[derive(Serialize)]
        struct TestContainer {
            test: Test,
        }

        #[test]
        fn supported_struct() {
            let test = Test {
                int: 1,
                seq: vec!["a", "b"],
            };

            let expected = r#"
                "int"       "1"
                "seq"       "a"
                "seq"       "b"
            "#;
            let result_str = to_string(&test).unwrap();
            log!(LogLevel::Debug, "Result:\n{}", result_str);

            // Remove all whitespace for assertion test.
            let result_str = result_str.replace(|c: char| c.is_whitespace(), "");
            let expected_str = expected.replace(|c: char| c.is_whitespace(), "");
            assert_eq!(result_str, expected_str);
        }

        #[test]
        fn supported_mapped_struct() {
            let test = Test {
                int: 1,
                seq: vec!["a", "b"],
            };
            let result = TestContainer { test };

            let expected = r#"
                "test"        
                {
                    "int"      "1"
                    "seq"       "a"
                    "seq"       "b"
                }
            "#;
            let result_str = format!("\n{}\n", to_string(&result).unwrap());
            log!(LogLevel::Debug, "Result:\n{}", result_str);

            // Remove all whitespace for assertion test.
            let result_str = result_str.replace(|c: char| c.is_whitespace(), "");
            let expected_str = expected.replace(|c: char| c.is_whitespace(), "");
            assert_eq!(result_str, expected_str);
        }
    }

    mod advanced {
        use super::*;

        #[test]
        fn test_struct_nested_list() {
            #[derive(Serialize)]
            struct Data {
                name: String,
                list_str: Vec<String>,
                map: std::collections::HashMap<String, i64>,
            }

            #[derive(Serialize)]
            struct Test {
                int: u32,
                seq: Vec<Data>,
            }
            #[derive(Serialize)]
            struct TestContainer {
                test: Test,
            }

            let test = Test {
                int: 1,
                seq: vec![
                    Data {
                        name: "Better VDF".to_string(),
                        list_str: vec![
                            "value1".to_string(),
                            "value2".to_string(),
                            "value3".to_string(),
                        ],
                        map: [
                            ("zbx".to_string(), 12318293),
                            ("thc".to_string(), -12393180),
                        ]
                        .iter()
                        .cloned()
                        .collect(),
                    },
                    Data {
                        name: "rrrrr".to_string(),
                        list_str: vec![
                            "1243".to_string(),
                            "sadferw".to_string(),
                            "batebt".to_string(),
                        ],
                        map: vec![("abc".to_string(), 444444), ("key".to_string(), -555555)]
                            .iter()
                            .cloned()
                            .collect(),
                    },
                ],
            };
            let result = TestContainer { test };

            let expected = r#"
            "test"
            {
                "seq"       
                {
                    "list_str" "value1"
                    "name"     "Better VDF"
                    "list_str" "value2"
                    "list_str" "value3"
                    "map"      
                    {
                        "thc"  "-12393180"
                        "zbx"  "12318293"
                    }
                }
                "int"      "1"
                "seq"       
                {
                    "name"     "rrrrr"
                    "list_str" "1243"
                    "list_str" "sadferw"
                    "list_str" "batebt"
                    "map"      
                    {
                        "key"  "-555555"
                        "abc"  "444444"
                    }
                }
            }
            "#;
            let result_str = to_string(&result).unwrap();
            log!(LogLevel::Debug, "Result:\n{}", result_str);

            // Remove all whitespace for assertion test.
            let result_str = result_str.replace(|c: char| c.is_whitespace(), "");
            let expected_str = preprocess(&expected, true, true).unwrap();
            log!(LogLevel::Debug, "Expected:\n{}", expected_str);
            let expected_str = expected_str.replace(|c: char| c.is_whitespace(), "");
            assert_eq!(result_str, expected_str);
        }
    }
}