Crate cel_core 

CEL-Core: High-level API for the Common Expression Language

This crate provides a unified Env for working with CEL expressions, following the cel-go architecture pattern.

Quick Start

use cel_core::Env;
use cel_core::CelType;

// Create an environment with standard library and a variable
let env = Env::with_standard_library()
    .with_variable("x", CelType::Int);

// Parse and type-check in one step
let ast = env.compile("x + 1").unwrap();
assert!(ast.is_checked());

Architecture

The Env struct coordinates:

• Parser: Converts source text into an AST
• Checker: Type-checks expressions and resolves references
• Variables: User-defined variable declarations
• Functions: Standard library + custom function declarations

Modules

• types: Core type system, AST, and declarations
• parser: Lexer, parser, and macro expansion
• checker: Type checking and overload resolution
• ext: Extension libraries (strings, math, encoders, optionals)

Proto Conversion

For proto wire format conversion (interop with cel-go, cel-cpp), use the cel-core-proto crate which provides CheckedExpr and ParsedExpr types.

Re-exports

pub use parser::parse;

pub use parser::ParseError;

pub use parser::ParseResult;

pub use types::proto::proto_message_to_cel_type;

pub use types::proto::ResolvedProtoType;

pub use types::BinaryOp;

pub use types::CelType;

pub use types::CelValue;

pub use types::ComprehensionData;

pub use types::Expr;

pub use types::FunctionDecl;

pub use types::ListElement;

pub use types::MapEntry;

pub use types::OverloadDecl;

pub use types::Span;

pub use types::Spanned;

pub use types::SpannedExpr;

pub use types::StructField;

pub use types::UnaryOp;

pub use types::VariableDecl;

Modules

ext

CEL extension libraries.

parser

CEL (Common Expression Language) parser.

time

Time parsing and formatting utilities for CEL timestamps and durations.

types

Common types for CEL: type system, values, AST, and declarations.

Structs

Abbreviations

A validated set of abbreviations mapping short names to fully-qualified names.

Ast

Unified AST representation matching cel-go’s Ast type.

CheckError

A type checking error.

CheckResult

Result of type checking an expression.

Duration

A CEL duration value.

EmptyActivation

An empty activation with no bindings.

EnumValue

A CEL enum value with type information.

Env

Unified environment for CEL expression processing.

EvalError

An error that occurred during CEL evaluation.

HierarchicalActivation

A hierarchical activation that delegates to a parent if not found locally.

MapActivation

A simple activation backed by a HashMap.

Program

A compiled CEL program ready for evaluation.

ReferenceInfo

Reference information for a resolved identifier or function.

SharedActivation

An activation that wraps an Arc for shared ownership.

StructFieldValue

An evaluated struct field ready for message construction.

Timestamp

A CEL timestamp value.

TypeValue

A CEL type value (runtime representation of types).

ValueError

Error returned when converting from Value to a specific type fails.

ValueMap

A CEL map with heterogeneous keys.

Enums

AbbrevError

Error when creating abbreviations.

AstError

Error type for Ast operations.

CheckErrorKind

The kind of type checking error.

CompileError

Error from compiling a CEL expression.

EvalErrorKind

The kind of evaluation error.

MapKey

A map key that supports CEL’s key types.

OptionalValue

A CEL optional value.

Value

A CEL runtime value.

Traits

Activation

Trait for resolving variable bindings during evaluation.

MessageValue

A trait representing a protobuf message value at runtime.

ProtoRegistry

Trait for protobuf runtime operations (evaluator operations).

ProtoTypeResolver

Trait for protobuf descriptor pool access (checker operations).

Functions

ast_to_string

Convert a CEL AST to source text.