Here is a list of all documented files with brief descriptions:

include
cel
parser
all.hpp	Includes the expression compiler and checked library registration interfaces. Prefer <cel/parser.hpp> for compilation or <cel/parser/lookup.hpp> for extensions. Compile and execute an expression:
compiler.hpp	Provides CEL expression compilation for clients with an owned operation registry. See <cel/parser/lookup.hpp> for library registrations
diagnostic.hpp
lookup.hpp	Provides owned type and operation registrations for extension libraries. Include <cel/parser/compiler.hpp> to compile expressions with a registry
parser.hpp	Provides UTF-8 expression compilation, checked library extensions, and source diagnostics