tanzim-parse 0.19.0

//! JSON parser (`json` feature).
//!
//! **Format:** `json`
//!
//! # Behaviour
//!
//! - Parses standard JSON with source spans. Objects become maps, arrays become lists, and
//!   strings/numbers/booleans become the matching scalar values; integers and floats are
//!   distinguished.
//! - Every node — root, map values, and list items — carries its span as a [`Location`]
//!   (line/column); for single-line input the line/column are omitted.
//! - JSON `null` becomes [`Value::Null`]. Non-UTF-8 input fails with [`Error::InvalidUtf8`], and any syntax error becomes
//!   [`Error::Parse`] with the failing position.
//! - [`is_format_supported`](crate::Parse::is_format_supported) returns `Some(true)` when
//!   the bytes parse as JSON, else `Some(false)`.
//!
//! # Example
//!
//! ```
//! use tanzim_parse::{Parse, json::Json};
//! use tanzim_source::SourceBuilder;
//!
//! let source = SourceBuilder::new()
//!     .with_source("file")
//!     .with_resource("config.json")
//!     .build()
//!     .unwrap();
//! let value = Json::new()
//!     .parse(&source, br#"{"host":"127.0.0.1"}"#, &[])
//!     .unwrap();
//! assert_eq!(
//!     value.value().as_map().unwrap().get("host").unwrap().value().as_string().unwrap(),
//!     "127.0.0.1"
//! );
//! ```

use crate::span::is_single_line;
use crate::{Parse, Source};
use cfg_if::cfg_if;
use spanned_json_parser::value::Value as JsonValue;
use spanned_json_parser::{Position, parse};
use tanzim_value::{Error, LocatedValue, Location, Map, Value};

/// Parser for the `json` format: standard JSON into a source-located value tree.
///
/// Objects, arrays, and scalars map to the value tree with a per-node span [`Location`]; JSON
/// `null` becomes [`Value::Null`]. Stateless — construct with [`Json::new`].
///
/// ```
/// use tanzim_parse::{Parse, json::Json};
/// use tanzim_source::SourceBuilder;
///
/// let source = SourceBuilder::new()
///     .with_source("file")
///     .with_resource("config.json")
///     .build()
///     .unwrap();
/// let value = Json::new().parse(&source, br#"{"port":8080}"#, &[]).unwrap();
/// let port = value.value().as_map().unwrap().get("port").unwrap();
/// assert_eq!(port.value().as_int().unwrap(), 8080);
/// ```
#[derive(Clone, Copy, Default)]
pub struct Json;

impl Json {
    /// Create a JSON parser.
    pub fn new() -> Self {
        Self
    }
}

impl Parse for Json {
    fn name(&self) -> &str {
        "JSON"
    }

    fn supported_format_list(&self) -> Vec<String> {
        vec!["json".into()]
    }

    fn parse(
        &self,
        src: &Source,
        bytes: &[u8],
        _other_source_list: &[Source],
    ) -> Result<LocatedValue, Error> {
        #[cfg(any(feature = "tracing", feature = "logging"))]
        let source = src.source();
        #[cfg(any(feature = "tracing", feature = "logging"))]
        let resource = src.resource();
        cfg_if! {
            if #[cfg(feature = "tracing")] {
                tracing::debug!(msg = "Parsing JSON configuration", source = source, resource = resource, bytes = bytes.len());
            } else if #[cfg(feature = "logging")] {
                log::debug!("msg=\"Parsing JSON configuration\" source={source} resource={resource} bytes={}", bytes.len());
            }
        }
        let text = match std::str::from_utf8(bytes) {
            Ok(value) => value,
            Err(_) => {
                return Err(Error::InvalidUtf8 {
                    location: Box::new(Location::in_source(src.clone(), None, None, None)),
                });
            }
        };
        let single_line = is_single_line(bytes);
        let parsed = match parse(text) {
            Ok(value) => value,
            Err(error) => {
                return Err(Error::Parse {
                    location: Some(Box::new(location_from_position(
                        src,
                        text,
                        single_line,
                        &error.start,
                        Some(&error.end),
                    ))),
                    message: format!("{:?}", error.kind),
                });
            }
        };
        let location =
            location_from_position(src, text, single_line, &parsed.start, Some(&parsed.end));
        let result = convert_value(
            src,
            text,
            single_line,
            parsed.value,
            &parsed.start,
            location,
        );
        if result.is_ok() {
            cfg_if! {
                if #[cfg(feature = "tracing")] {
                    tracing::trace!(msg = "Parsed JSON configuration", source = source, resource = resource);
                } else if #[cfg(feature = "logging")] {
                    log::trace!("msg=\"Parsed JSON configuration\" source={source} resource={resource}");
                }
            }
        }
        result
    }

    fn is_format_supported(&self, bytes: &[u8]) -> Option<bool> {
        match std::str::from_utf8(bytes) {
            Ok(text) => Some(parse(text).is_ok()),
            Err(_) => Some(false),
        }
    }
}

/// Serialize a [`Value`] tree into pretty-printed JSON (2-space indent).
///
/// Accepts a [`Value`], `&Value`, [`LocatedValue`], or `&LocatedValue`. `source` is
/// accepted for signature symmetry with [`Parse::parse`] but is unused here.
///
/// ```
/// use tanzim_parse::json::unparse;
/// use tanzim_source::SourceBuilder;
/// use tanzim_value::{Map, LocatedValue, Location, Value};
///
/// let source = SourceBuilder::new().with_source("file").build().unwrap();
/// let mut map = Map::new();
/// map.insert("port".into(), LocatedValue::new(
///     Value::Int(8080),
///     Location::at("file", "", None, None, None),
/// ));
/// let text = unparse(&source, Value::Map(map)).unwrap();
/// assert_eq!(text, "{\n  \"port\": 8080\n}");
/// ```
pub fn unparse<V: AsRef<Value>>(
    _source: &Source,
    value: V,
) -> Result<String, Box<dyn std::error::Error + Send + Sync + 'static>> {
    let mut out = String::new();
    write_json(&mut out, value.as_ref(), 0)?;
    Ok(out)
}

fn write_json(
    out: &mut String,
    value: &Value,
    indent: usize,
) -> Result<(), Box<dyn std::error::Error + Send + Sync + 'static>> {
    match value {
        Value::Bool(value) => out.push_str(if *value { "true" } else { "false" }),
        Value::Int(value) => out.push_str(&value.to_string()),
        Value::Float(value) => {
            if !value.is_finite() {
                return Err(format!("cannot serialize non-finite float {value} as JSON").into());
            }
            out.push_str(&format!("{value:?}"));
        }
        Value::String(value) => write_json_string(out, value),
        Value::List(values) => {
            if values.is_empty() {
                out.push_str("[]");
                return Ok(());
            }
            out.push_str("[\n");
            for (index, item) in values.iter().enumerate() {
                push_indent(out, indent + 1);
                write_json(out, item.value(), indent + 1)?;
                if index + 1 < values.len() {
                    out.push(',');
                }
                out.push('\n');
            }
            push_indent(out, indent);
            out.push(']');
        }
        Value::Map(map) => {
            let entries = map.entries();
            if entries.is_empty() {
                out.push_str("{}");
                return Ok(());
            }
            out.push_str("{\n");
            for (index, (key, item)) in entries.iter().enumerate() {
                push_indent(out, indent + 1);
                write_json_string(out, key);
                out.push_str(": ");
                write_json(out, item.value(), indent + 1)?;
                if index + 1 < entries.len() {
                    out.push(',');
                }
                out.push('\n');
            }
            push_indent(out, indent);
            out.push('}');
        }
        Value::Null => out.push_str("null"),
    }
    Ok(())
}

fn push_indent(out: &mut String, indent: usize) {
    for _ in 0..indent {
        out.push_str("  ");
    }
}

fn write_json_string(out: &mut String, value: &str) {
    out.push('"');
    for ch in value.chars() {
        match ch {
            '"' => out.push_str("\\\""),
            '\\' => out.push_str("\\\\"),
            '\n' => out.push_str("\\n"),
            '\r' => out.push_str("\\r"),
            '\t' => out.push_str("\\t"),
            control if (control as u32) < 0x20 => {
                out.push_str(&format!("\\u{:04x}", control as u32));
            }
            other => out.push(other),
        }
    }
    out.push('"');
}

fn convert_value(
    source: &Source,
    text: &str,
    single_line: bool,
    value: JsonValue,
    _start: &Position,
    location: Location,
) -> Result<LocatedValue, Error> {
    match value {
        JsonValue::Null => Ok(LocatedValue::new(Value::Null, location)),
        JsonValue::Bool(value) => Ok(LocatedValue::new(Value::Bool(value), location)),
        JsonValue::Number(number) => match number {
            spanned_json_parser::value::Number::PosInt(value) => {
                Ok(LocatedValue::new(Value::Int(value as isize), location))
            }
            spanned_json_parser::value::Number::NegInt(value) => {
                Ok(LocatedValue::new(Value::Int(value as isize), location))
            }
            spanned_json_parser::value::Number::Float(value) => {
                Ok(LocatedValue::new(Value::Float(value), location))
            }
        },
        JsonValue::String(value) => Ok(LocatedValue::new(Value::String(value), location)),
        JsonValue::Array(values) => {
            let mut list = Vec::new();
            for item in &values {
                let item_location =
                    location_from_position(source, text, single_line, &item.start, Some(&item.end));
                let converted = convert_value(
                    source,
                    text,
                    single_line,
                    item.value.clone(),
                    &item.start,
                    item_location,
                )?;
                list.push(converted);
            }
            Ok(LocatedValue::new(Value::List(list), location))
        }
        JsonValue::Object(values) => {
            let mut map = Map::new();
            for (key, item) in values {
                let item_location =
                    location_from_position(source, text, single_line, &item.start, Some(&item.end));
                let converted = convert_value(
                    source,
                    text,
                    single_line,
                    item.value.clone(),
                    &item.start,
                    item_location,
                )?;
                map.insert(key, converted);
            }
            Ok(LocatedValue::new(Value::Map(map), location))
        }
    }
}

fn location_from_position(
    source: &Source,
    text: &str,
    single_line: bool,
    start: &Position,
    end: Option<&Position>,
) -> Location {
    if single_line {
        return Location::in_source(source.clone(), None, None, None);
    }
    let mut length = None;
    if let Some(end) = end
        && start.line == end.line
        && end.col >= start.col
    {
        length = Some(end.col - start.col + 1);
    }
    Location::in_text(
        source.clone(),
        text,
        Some(start.line),
        Some(start.col),
        length,
    )
}