Crate fel_core 

FEL parser, evaluator, and dependency analysis with base-10 decimal arithmetic.

Uses rust_decimal for base-10 arithmetic per spec S3.4.1 (minimum 18 significant digits).

Docs

• Human overview: crate README.md (architecture, pipeline, module map).
• API reference: cargo doc -p fel-core --no-deps --open.
• Markdown API export: docs/rustdoc-md/API.md (see crate README).

Re-exports

pub use ast::Expr;

pub use context_json::formspec_environment_from_json_map;

pub use convert::fel_to_json;

pub use convert::field_map_from_json_str;

pub use convert::json_object_to_field_map;

pub use convert::json_to_fel;

pub use dependencies::Dependencies;

pub use dependencies::dependencies_to_json_value;

pub use dependencies::dependencies_to_json_value_styled;

pub use dependencies::extract_dependencies;

pub use environment::FormspecEnvironment;

pub use environment::MipState;

pub use environment::RepeatContext;

pub use error::Diagnostic;

pub use error::FelError;

pub use error::Severity;

pub use error::has_error_diagnostics;

pub use error::reject_undefined_functions;

pub use error::undefined_function_names_from_diagnostics;

pub use evaluator::Environment;

pub use evaluator::EvalResult;

pub use evaluator::Evaluator;

pub use evaluator::MapEnvironment;

pub use evaluator::evaluate;

pub use evaluator::evaluate_with_trace;

pub use extensions::BuiltinFunctionCatalogEntry;

pub use extensions::ExtensionError;

pub use extensions::ExtensionRegistry;

pub use extensions::builtin_function_catalog;

pub use extensions::builtin_function_catalog_json_value;

pub use interpolation::expr_is_interpolation_static_literal;

pub use iso_duration::IsoDurationParse;

pub use iso_duration::parse_iso8601_duration;

pub use iso_duration::parse_iso8601_duration_ms;

pub use lexer::is_valid_fel_identifier;

pub use lexer::sanitize_fel_identifier;

pub use parser::parse;

pub use prepare_host::PrepareFelHostInput;

pub use prepare_host::PrepareFelHostOptionsOwned;

pub use prepare_host::prepare_fel_expression_for_host;

pub use prepare_host::prepare_fel_expression_owned;

pub use prepare_host::prepare_fel_host_options_from_json_map;

pub use printer::print_expr;

pub use trace::Trace;

pub use trace::TraceStep;

pub use types::FelDate;

pub use types::FelMoney;

pub use types::FelValue;

pub use types::parse_date_literal;

pub use types::parse_datetime_literal;

pub use wire_style::JsonWireStyle;

Modules

ast

FEL abstract syntax tree node definitions and operators.

context_json

Build FormspecEnvironment from JSON-shaped evaluation context.

convert

Canonical conversion between serde_json::Value and FelValue.

dependencies

Static dependency extraction — field refs, context refs, and MIP dependencies.

environment

FEL evaluation environment with field resolution, repeats, MIP state, and instances.

error

FEL error types and diagnostic messages.

evaluator

FEL tree-walking evaluator with base-10 decimal arithmetic and null propagation.

extensions

FEL extension function registry with null propagation and conflict detection.

interpolation

Helpers for {{expression}} message interpolation (locale spec §3.3.1).

iso_duration

ISO 8601 duration parsing for FEL duration().

lexer

FEL hand-rolled lexer — tokenization with spans and decimal numbers.

parser

FEL hand-rolled recursive descent parser with operator precedence.

prepare_host

FEL source normalization before host evaluation (parity with TS normalizeExpressionForWasmEvaluation).

printer

FEL AST to string serializer for expression rewriting and debugging.

trace

Structured evaluation traces for FEL.

types

FEL runtime value types with base-10 decimal arithmetic.

wire_style

Host JSON key convention shared across FEL dependency wire and Formspec FFI surfaces.

Structs

Decimal

Decimal represents a 128 bit representation of a fixed-precision decimal number. The finite set of values of type Decimal are of the form m / 10^e, where m is an integer such that -2⁹⁶ < m < 2⁹⁶, and e is an integer between 0 and 28 inclusive.

PositionedToken

One lexeme from tokenize for host bindings and tooling (stable type names + source span).

Functions

eval_with_fields

Parse and evaluate a FEL expression with a flat field map.

fel_diagnostics_to_json_value

Evaluation diagnostics as JSON objects (message, severity wire string).

tokenize

Tokenize FEL source into PositionedTokens (lexical analysis only; no parse).

tokenize_to_json_value

FEL lexer tokens as JSON (camelCase keys) for host bindings.