hocon/

lib.rs

//! # hocon
//!
//! Full [Lightbend HOCON specification](https://github.com/lightbend/config/blob/main/HOCON.md)-compliant
//! parser for Rust.
//!
//! ## Quick Example
//!
//! ```rust
//! # fn main() -> Result<(), Box<dyn std::error::Error>> {
//! let config = hocon::parse(r#"
//!     server {
//!         host = "localhost"
//!         port = 8080
//!     }
//! "#)?;
//!
//! assert_eq!(config.get_string("server.host")?, "localhost");
//! assert_eq!(config.get_i64("server.port")?, 8080);
//! # Ok(())
//! # }
//! ```
//!
//! ## Parsing
//!
//! - [`parse`] -- parse a HOCON string into a [`Config`].
//! - [`parse_file`] -- parse a HOCON file. Include directives are resolved
//!   relative to the file's directory.
//! - [`parse_with_env`] / [`parse_file_with_env`] -- parse with a custom
//!   environment variable map instead of inheriting the process environment.
//!
//! ## Accessing Values
//!
//! [`Config`] provides typed getters that accept dot-separated paths:
//!
//! | Method | Return type |
//! |--------|-------------|
//! | [`Config::get_string`] | `Result<String, ConfigError>` |
//! | [`Config::get_i64`] | `Result<i64, ConfigError>` |
//! | [`Config::get_f64`] | `Result<f64, ConfigError>` |
//! | [`Config::get_bool`] | `Result<bool, ConfigError>` |
//! | [`Config::get_config`] | `Result<Config, ConfigError>` |
//! | [`Config::get_list`] | `Result<Vec<HoconValue>, ConfigError>` |
//! | [`Config::get_duration`] | `Result<Duration, ConfigError>` |
//! | [`Config::get_bytes`] | `Result<i64, ConfigError>` |
//!
//! Each typed getter has an `_option` variant (e.g., [`Config::get_string_option`])
//! that returns `Option<T>` instead.
//!
//! ## Duration and Byte-Size Values
//!
//! ```rust
//! # fn main() -> Result<(), Box<dyn std::error::Error>> {
//! let config = hocon::parse(r#"
//!     timeout = 30 seconds
//!     max-upload = 512 MB
//! "#)?;
//!
//! let timeout = config.get_duration("timeout")?;
//! let max_upload = config.get_bytes("max-upload")?;
//! # Ok(())
//! # }
//! ```
//!
//! Duration units: `ns`, `us`, `ms`, `s`/`seconds`, `m`/`minutes`, `h`/`hours`, `d`/`days`.
//!
//! Byte-size units: `B`, `KB`, `KiB`, `MB`, `MiB`, `GB`, `GiB`, `TB`, `TiB`
//! (and their long forms like `megabytes`, `mebibytes`).
//!
//! ## Serde Deserialization
//!
//! With the `serde` feature enabled, deserialize a [`Config`] (or sub-config)
//! into any type implementing `serde::Deserialize`:
//!
//! ```rust,ignore
//! use serde::Deserialize;
//!
//! #[derive(Deserialize)]
//! struct Server {
//!     host: String,
//!     port: u16,
//! }
//!
//! let server: Server = config.get_config("server")?.deserialize()?;
//! ```
//!
//! ## Include Files
//!
//! HOCON supports `include` directives to compose configuration from multiple files:
//!
//! ```hocon
//! include "defaults.conf"
//!
//! server.port = 9090  # override a value from defaults
//! ```
//!
//! When parsing with [`parse_file`], include paths are resolved relative to the
//! file being parsed.
//!
//! ## Error Types
//!
//! - [`HoconError`] -- unified error returned by parse functions. Wraps:
//!   - [`ParseError`] -- syntax errors during lexing or parsing (includes line/column).
//!   - [`ResolveError`] -- substitution resolution failures, cycle detection.
//!   - `std::io::Error` -- file I/O errors (top-level file read; include file errors appear as [`ResolveError`]).
//! - [`ConfigError`] -- missing keys or type mismatches when accessing values.
//!
//! ## HOCON Specification
//!
//! For the full specification, see the
//! [Lightbend HOCON spec](https://github.com/lightbend/config/blob/main/HOCON.md).

#[cfg(any(
    feature = "adapters-properties",
    feature = "adapters-env",
    feature = "adapters-jsonc",
    feature = "adapters-toml",
    feature = "adapters-yaml",
))]
pub mod adapters;
pub mod config;
pub mod error;
/// Internal lexer module. Not part of the stable public API.
///
/// This module is `pub` to allow integration tests to access internal types.
/// All items are subject to change without notice across minor versions.
/// Prefer the re-exported items (`tokenize`, `Token`, etc.) over direct module access.
#[doc(hidden)]
pub mod lexer;
pub(crate) mod numeric_array;
pub mod options;
/// Internal parser module. Not part of the stable public API.
///
/// This module is `pub` to allow integration tests to access internal types.
/// All items are subject to change without notice across minor versions.
#[doc(hidden)]
pub mod parser;
pub(crate) mod properties;
/// Internal resolver module. Not part of the stable public API.
///
/// This module is `pub` to allow integration tests to access internal types
/// (`build_tree`, `resolve_tree`, `merge_unresolved`, `ResObj`, etc.).
/// All items are subject to change without notice across minor versions.
#[doc(hidden)]
pub mod resolver;
pub(crate) mod sysenv;
pub mod value;
mod value_factory;

#[cfg(feature = "serde")]
pub mod serde;

pub use config::{Config, Period};
pub use error::{ConfigError, HoconError, NotResolvedError, ParseError, ResolveError};
pub use options::{ParseOptions, ResolveOptions};
pub use value::{HoconValue, ScalarType, ScalarValue};
pub use value_factory::empty;

#[cfg(feature = "serde")]
pub use value_factory::from_map;

// Lexer surface intentionally narrow — only the items integration tests
// and diagnostic tooling need. The full lexer module is not part of the
// public API.
pub use lexer::{tokenize, Segment, SubstPayload, Token, TokenKind};

#[cfg(feature = "serde")]
pub use serde::{from_value, DeserializeError};

use std::collections::HashMap;
use std::path::Path;

// ── include-package feature: public Parser builder ───────────────────────────

/// Builder-style parser with a per-instance package registry for
/// `include package(...)` support (E11).
///
/// # Feature flag
///
/// This type is only available when the `include-package` Cargo feature is
/// enabled:
///
/// ```toml
/// [dependencies]
/// hocon-parser = { version = "...", features = ["include-package"] }
/// ```
///
/// # Usage
///
/// ```rust,ignore
/// # #[cfg(feature = "include-package")]
/// # fn main() -> Result<(), Box<dyn std::error::Error>> {
/// let config = hocon::Parser::new()
///     .register_package("github.com/org/pkg", "reference.conf", include_str!("conf/reference.conf"))
///     .parse_file("app.conf")?;
/// # Ok(())
/// # }
/// ```
///
/// # Cascade convention
///
/// For packages that depend on other HOCON-config-providing packages, follow
/// this convention to cascade registrations:
///
/// ```rust,ignore
/// // In your package (e.g., pkg_a/src/hocon.rs):
/// pub fn register(parser: hocon::Parser) -> hocon::Parser {
///     let parser = parser
///         .register_package("github.com/org/pkg_a", "reference.conf", include_str!("../conf/reference.conf"));
///     // Cascade to dependencies:
///     // let parser = pkg_b::hocon::register(parser);
///     parser
/// }
/// ```
///
/// Callers:
/// ```rust,ignore
/// let config = pkg_a::hocon::register(hocon::Parser::new())
///     .parse_file("app.conf")?;
/// ```
///
/// # Collision policy
///
/// Registering two **different** content strings for the same `(identifier, file)`
/// key **panics** — this is a programming error (setup-time invariant). Re-registering
/// **byte-identical** content is idempotent (no panic).
#[cfg(feature = "include-package")]
pub struct Parser {
    registry: HashMap<(String, String), String>,
}

#[cfg(feature = "include-package")]
impl Default for Parser {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(feature = "include-package")]
impl Parser {
    /// Create a new `Parser` with an empty package registry.
    pub fn new() -> Self {
        Parser {
            registry: HashMap::new(),
        }
    }

    /// Register HOCON content for an `include package("identifier", "file")`
    /// include statement.
    ///
    /// # Arguments
    ///
    /// * `identifier` — the package identifier (e.g., `"github.com/org/pkg"`).
    ///   Should follow Go-module-path style for cross-impl portability (E11 decision 1),
    ///   but any non-empty string is accepted by the parser.
    /// * `file` — the file path within the package (e.g., `"reference.conf"`).
    ///   Must satisfy E11 decision 6 constraints.
    /// * `content` — the HOCON source text. Typically loaded via `include_str!`.
    ///   Empty content is valid and contributes `{}` to the merge.
    ///
    /// # Panics
    ///
    /// Panics if different content is registered for the same `(identifier, file)` pair.
    /// Re-registering byte-identical content is idempotent (no panic).
    ///
    /// # Example
    ///
    /// ```rust,ignore
    /// let parser = hocon::Parser::new()
    ///     .register_package("github.com/org/pkg", "reference.conf", include_str!("conf/reference.conf"))
    ///     .register_package("github.com/org/pkg", "overrides.conf", include_str!("conf/overrides.conf"));
    /// ```
    pub fn register_package(
        mut self,
        identifier: impl Into<String>,
        file: impl Into<String>,
        content: impl Into<String>,
    ) -> Self {
        let id = identifier.into();
        let f = file.into();
        let c = content.into();
        if let Some(existing) = self.registry.get(&(id.clone(), f.clone())) {
            if existing != &c {
                panic!(
                    "hocon: conflicting content registered for package ({:?}, {:?}): \
                     different content already registered for this (identifier, file) pair",
                    id, f
                );
            }
            // byte-identical: idempotent, no-op
        } else {
            self.registry.insert((id, f), c);
        }
        self
    }

    /// Parse a HOCON string using the registered package registry.
    ///
    /// Inherits the process environment, skipping entries whose name or value
    /// is not valid UTF-8; such a variable resolves as if it were unset.
    pub fn parse(self, input: &str) -> Result<Config, HoconError> {
        self.parse_with_env(input, &sysenv::vars().collect())
    }

    /// Parse a HOCON file using the registered package registry.
    ///
    /// Inherits the process environment, skipping entries whose name or value
    /// is not valid UTF-8; such a variable resolves as if it were unset.
    pub fn parse_file(self, path: impl AsRef<Path>) -> Result<Config, HoconError> {
        self.parse_file_with_env(path, &sysenv::vars().collect())
    }

    /// Parse a HOCON string with a custom environment map and the registered registry.
    pub fn parse_with_env(
        self,
        input: &str,
        env: &HashMap<String, String>,
    ) -> Result<Config, HoconError> {
        self.parse_with_options(input, ParseOptions::defaults().with_env(env.clone()))
    }

    /// Parse a HOCON file with a custom environment map and the registered registry.
    pub fn parse_file_with_env(
        self,
        path: impl AsRef<Path>,
        env: &HashMap<String, String>,
    ) -> Result<Config, HoconError> {
        self.parse_file_with_options(path, ParseOptions::defaults().with_env(env.clone()))
    }

    /// Parse a HOCON string with explicit [`ParseOptions`] and the registered registry.
    ///
    /// Equivalent to the module-level [`parse_string_with_options`] but threads the
    /// per-`Parser` package registry through phase 1, enabling
    /// `include package("identifier", "file")` to resolve against `register_package`-supplied
    /// content. Supports both fused (`resolve_substitutions = true`, default) and deferred
    /// (`resolve_substitutions = false`) lifecycles. The latter returns an unresolved
    /// `Config` whose `Config::resolve` call performs phase 2 — includes are already
    /// inlined at phase 1 so the registry is not needed after this call returns.
    pub fn parse_with_options(self, input: &str, opts: ParseOptions) -> Result<Config, HoconError> {
        let tokens = lexer::tokenize(input)?;
        // S3.1 (corrected, xx.hocon E10): an empty / whitespace-only /
        // comment-only / BOM-only document parses to the empty object per the
        // HOCON.md L134-136 brace-omission relaxation — no emptiness guard.
        let ast = parser::parse_tokens(&tokens)?;
        reject_array_root(&ast, opts.origin_description.as_deref().unwrap_or("input"))?;

        let env: HashMap<String, String> = opts.env.clone().unwrap_or_else(|| {
            if opts.resolve_substitutions {
                sysenv::vars().collect()
            } else {
                HashMap::new()
            }
        });

        let internal_opts = self.into_resolve_opts(env, opts.base_dir.clone());

        if opts.resolve_substitutions {
            let value = resolver::resolve(ast, &internal_opts)?;
            match value {
                HoconValue::Object(fields) => {
                    let mut cfg = Config::new(fields);
                    cfg.parse_base_dir = opts.base_dir;
                    cfg.origin_description = opts.origin_description;
                    Ok(cfg)
                }
                _ => Err(HoconError::Parse(ParseError {
                    message: "root must be an object".into(),
                    line: 1,
                    col: 1,
                })),
            }
        } else {
            let tree = resolver::build_tree(ast, &internal_opts)?;
            Ok(Config::new_from_res_obj(
                tree,
                opts.base_dir,
                opts.origin_description,
            ))
        }
    }

    /// Parse a HOCON file with explicit [`ParseOptions`] and the registered registry.
    /// File's parent directory is used as base_dir (overrides `opts.base_dir`).
    pub fn parse_file_with_options(
        self,
        path: impl AsRef<Path>,
        opts: ParseOptions,
    ) -> Result<Config, HoconError> {
        let path = path.as_ref();
        let content = std::fs::read_to_string(path)
            .map_err(|e| std::io::Error::new(e.kind(), format!("{}: {}", path.display(), e)))?;
        let base_dir = path.parent().map(|p| p.to_path_buf());
        // Default the origin to the file path so diagnostics (e.g. the S3.5
        // array-at-file-root error) name the file, matching Lightbend origins.
        let origin_description = opts
            .origin_description
            .or_else(|| Some(path.display().to_string()));
        let opts = ParseOptions {
            base_dir,
            origin_description,
            ..opts
        };
        self.parse_with_options(&content, opts)
    }

    /// Convert this `Parser` into `ResolveOptions`, threading the registry in.
    fn into_resolve_opts(
        self,
        env: HashMap<String, String>,
        base_dir: Option<std::path::PathBuf>,
    ) -> resolver::InternalResolveOptions {
        let mut opts = resolver::InternalResolveOptions::new(env);
        if let Some(dir) = base_dir {
            opts = opts.with_base_dir(dir);
        }
        opts.package_registry = std::sync::Arc::new(self.registry);
        opts
    }
}

/// Parse a HOCON string into a Config.
///
/// Inherits the process environment for `${VAR}` resolution. Entries whose
/// name or value is not valid UTF-8 are skipped rather than converted
/// lossily, so such a variable resolves as if it were unset: `${?VAR}` is
/// undefined and `${VAR}` is the usual unresolved-substitution error. A
/// non-UTF-8 name is unreachable from UTF-8 HOCON source anyway.
pub fn parse(input: &str) -> Result<Config, HoconError> {
    parse_with_env(input, &sysenv::vars().collect())
}

/// Parse a HOCON string with explicit [`ParseOptions`].
///
/// `opts.resolve_substitutions = true` (default): fused parse + resolve, same
/// as [`parse`]. `opts.resolve_substitutions = false`: phase 1 only; returned
/// `Config` may have `is_resolved() = false`. Use [`Config::resolve`] later.
///
/// This module-level function does **not** thread a package registry — for that,
/// use [`Parser::parse_with_options`] (feature `include-package`).
pub fn parse_string_with_options(input: &str, opts: ParseOptions) -> Result<Config, HoconError> {
    let tokens = lexer::tokenize(input)?;
    let ast = parser::parse_tokens(&tokens)?;
    reject_array_root(&ast, opts.origin_description.as_deref().unwrap_or("input"))?;

    let env: HashMap<String, String> = opts.env.clone().unwrap_or_else(|| {
        if opts.resolve_substitutions {
            sysenv::vars().collect()
        } else {
            HashMap::new()
        }
    });

    let mut internal_opts = resolver::InternalResolveOptions::new(env);
    if let Some(ref bd) = opts.base_dir {
        internal_opts = internal_opts.with_base_dir(bd.clone());
    }

    if opts.resolve_substitutions {
        // Fused path: phase 1 + phase 2.
        let value = resolver::resolve(ast, &internal_opts)?;
        match value {
            HoconValue::Object(fields) => {
                let mut cfg = Config::new(fields);
                cfg.parse_base_dir = opts.base_dir;
                cfg.origin_description = opts.origin_description;
                Ok(cfg)
            }
            _ => Err(HoconError::Parse(ParseError {
                message: "root must be an object".into(),
                line: 1,
                col: 1,
            })),
        }
    } else {
        // Deferred path: phase 1 only.
        let tree = resolver::build_tree(ast, &internal_opts)?;
        Ok(Config::new_from_res_obj(
            tree,
            opts.base_dir,
            opts.origin_description,
        ))
    }
}

/// Parse a HOCON file with explicit [`ParseOptions`].
/// File's parent directory is used as base_dir (overrides opts.base_dir).
pub fn parse_file_with_options<P: AsRef<Path>>(
    path: P,
    opts: ParseOptions,
) -> Result<Config, HoconError> {
    let path = path.as_ref();
    let content = std::fs::read_to_string(path)
        .map_err(|e| std::io::Error::new(e.kind(), format!("{}: {}", path.display(), e)))?;
    let base_dir = path.parent().map(|p| p.to_path_buf());
    // Default the origin to the file path so diagnostics (e.g. the S3.5
    // array-at-file-root error) name the file, matching Lightbend origins.
    let origin_description = opts
        .origin_description
        .or_else(|| Some(path.display().to_string()));
    let opts = ParseOptions {
        base_dir,
        origin_description,
        ..opts
    };
    parse_string_with_options(&content, opts)
}

/// Parse a HOCON file into a Config.
///
/// Inherits the process environment for `${VAR}` resolution. Entries whose
/// name or value is not valid UTF-8 are skipped rather than converted
/// lossily, so such a variable resolves as if it were unset: `${?VAR}` is
/// undefined and `${VAR}` is the usual unresolved-substitution error. A
/// non-UTF-8 name is unreachable from UTF-8 HOCON source anyway.
pub fn parse_file<P: AsRef<Path>>(path: P) -> Result<Config, HoconError> {
    parse_file_with_env(path, &sysenv::vars().collect())
}

/// Parse a HOCON file with a custom environment variable map.
pub fn parse_file_with_env<P: AsRef<Path>>(
    path: P,
    env: &HashMap<String, String>,
) -> Result<Config, HoconError> {
    let path = path.as_ref();
    let content = std::fs::read_to_string(path)
        .map_err(|e| std::io::Error::new(e.kind(), format!("{}: {}", path.display(), e)))?;
    let tokens = lexer::tokenize(&content)?;
    let ast = parser::parse_tokens(&tokens)?;
    reject_array_root(&ast, &path.display().to_string())?;
    let mut opts = resolver::InternalResolveOptions::new(env.clone());
    if let Some(dir) = path.parent() {
        opts = opts.with_base_dir(dir.to_path_buf());
    }
    let value = resolver::resolve(ast, &opts)?;
    match value {
        HoconValue::Object(fields) => Ok(Config::new(fields)),
        _ => Err(HoconError::Parse(ParseError {
            message: "root must be an object".into(),
            line: 1,
            col: 1,
        })),
    }
}

/// S3.5 (HOCON.md L989-991): an array-root document is valid syntax, but the
/// object-rooted Config API rejects it at the Config boundary with a TYPE
/// error, matching Lightbend's `Parseable.forceParsedToObject`
/// (`ConfigException.WrongType` "has type LIST rather than object at file
/// root"). The message carries the origin and the opening bracket's position.
fn reject_array_root(ast: &parser::AstNode, origin: &str) -> Result<(), HoconError> {
    if let parser::AstNode::Array { pos, .. } = ast {
        return Err(HoconError::Config(ConfigError {
            message: format!(
                "{}: {}:{}: document has type array rather than object at file root (HOCON.md L989-991); the Config API requires an object at file root",
                origin, pos.line, pos.col
            ),
            path: String::new(),
        }));
    }
    Ok(())
}

/// Parse a HOCON string with a custom environment variable map.
pub fn parse_with_env(input: &str, env: &HashMap<String, String>) -> Result<Config, HoconError> {
    let tokens = lexer::tokenize(input)?;
    let ast = parser::parse_tokens(&tokens)?;
    reject_array_root(&ast, "input")?;
    let opts = resolver::InternalResolveOptions::new(env.clone());
    let value = resolver::resolve(ast, &opts)?;
    match value {
        HoconValue::Object(fields) => Ok(Config::new(fields)),
        _ => Err(HoconError::Parse(ParseError {
            message: "root must be an object".into(),
            line: 1,
            col: 1,
        })),
    }
}

/// Internal JSON renderer for use by Layer-2 fixture tests.
///
/// Emits compact sorted-key JSON. Not semver-stable.
/// Callers: `tests/deferred_resolution_fixtures.rs`.
#[doc(hidden)]
pub fn _render_json_for_test(config: &Config) -> String {
    use crate::value::HoconValue;
    use std::fmt::Write;

    fn render_value(val: &HoconValue, out: &mut String) {
        match val {
            HoconValue::Scalar(sv) => {
                use crate::value::ScalarType;
                match sv.value_type {
                    ScalarType::Null => out.push_str("null"),
                    ScalarType::Boolean => out.push_str(&sv.raw),
                    ScalarType::Number => out.push_str(&sv.raw),
                    ScalarType::String => {
                        let escaped = sv
                            .raw
                            .replace('\\', "\\\\")
                            .replace('"', "\\\"")
                            .replace('\n', "\\n")
                            .replace('\r', "\\r")
                            .replace('\t', "\\t");
                        let _ = write!(out, "\"{}\"", escaped);
                    }
                }
            }
            HoconValue::Object(map) => {
                out.push('{');
                let mut keys: Vec<&str> = map.keys().map(|s| s.as_str()).collect();
                keys.sort_unstable();
                for (i, k) in keys.iter().enumerate() {
                    if i > 0 {
                        out.push(',');
                    }
                    let _ = write!(out, "\"{}\":", k);
                    render_value(map.get(*k).unwrap(), out);
                }
                out.push('}');
            }
            HoconValue::Array(arr) => {
                out.push('[');
                for (i, v) in arr.iter().enumerate() {
                    if i > 0 {
                        out.push(',');
                    }
                    render_value(v, out);
                }
                out.push(']');
            }
            HoconValue::Placeholder(pv) => {
                let _ = write!(out, "\"<unresolved:{}>\"", pv.path);
            }
        }
    }

    let mut out = String::from("{");
    let mut keys: Vec<&str> = config.root.keys().map(|s| s.as_str()).collect();
    keys.sort_unstable();
    for (i, k) in keys.iter().enumerate() {
        if i > 0 {
            out.push(',');
        }
        let _ = write!(out, "\"{}\":", k);
        render_value(config.root.get(*k).unwrap(), &mut out);
    }
    out.push('}');
    out
}