Mike Gerwitz
cf2cd882ca
This introduces `Nt := (A | ... | Z);`, where `Nt` is the name of the nonterminal and `A ... Z` are the inner nonterminals---it produces a parser that provides a choice between a set of nonterminals. This is implemented efficiently by understanding the QName that is accepted by each of the inner nonterminals and delegating that token immediately to the appropriate parser. This is a benefit of using a parser generator macro over parser combinators---we do not need to implement backtracking by letting inner parsers fail, because we know ahead of time exactly what parser we need. This _does not_ verify that each of the inner parsers accept a unique QName; maybe at a later time I can figure out something for that. However, because this compiles into a `match`, there is no ambiguity---like a PEG parser, there is precedence in the face of an ambiguous token, and the first one wins. Consequently, tests would surely fail, since the latter wouldn't be able to be parsed. This also demonstrates how we can have good error suggestions for this parsing framework: because the inner nonterminals and their QNames are known at compile time, error messages simply generate a list of QNames that are expected. The error recovery strategy is the same as previously noted, and subject to the same concerns, though it may be more appropriate here: it is desirable for the inner parser to fail rather than retrying, so that the sum parser is able to fail and, once the Kleene operator is introduced, retry on another potential element. But again, that recovery strategy may happen to work in some cases, but'll fail miserably in others (e.g. placing an unknown element at the head of a block that expects a sequence of elements would potentially fail the entire block rather than just the invalid one). But more to come on that later; it's not critical at this point. I need to get parsing completed for TAME's input language. DEV-7145 |
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| Makefile.am | ||
| README.md | ||
| autogen.sh | ||
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README.md
TAME in Rust (TAMER)
TAME was written to help tame the complexity of developing comparative insurance rating systems. This project aims to tame the complexity and performance issues of TAME itself. TAMER is therefore more tame than TAME.
TAME was originally written in XSLT. For more information about the
project, see the parent README.md.
Building
To bootstrap from the source repository, run ./bootstrap.
To configure the build for your system, run ./configure. To build, run
make. To run tests, run make check.
You may also invoke cargo directly, which make will do for you using
options provided to configure.
Note that the default development build results in terrible runtime performance! See [#Build Flags][] below for instructions on how to generate a release binary.
Build Flags
The environment variable CARGO_BUILD_FLAGS can be used to provide
additional arguments to cargo build when invoked via make. This can be
provided optionally during configure and can be overridden when invoking
make. For example:
# release build
$ ./configure && make CARGO_BUILD_FLAGS=--release
$ ./configure CARGO_BUILD_FLAGS=--release && make
# dev build
$ ./configure && make
$ ./configure CARGO_BUILD_FLAGS=--release && make CARGO_BUILD_FLAGS=
Hacking
This section contains advice for those developing TAMER.
Running Tests
Developers should be using test-driven development (TDD). make check will
run all necessary tests.
Code Format
Rust provides rustfmt that can automatically format code for you. This
project mandates its use and therefore eliminates personal preference in
code style (for better or worse).
Formatting checks are run during make check and, on failure, will output
the diff that would be applied if you ran make fmt (or make fix); this
will run cargo fmt for you (and will use the binaries configured via
configure).
Since developers should be doing test-driven development (TDD) and therefore
should be running make check frequently, the hope is that frequent
feedback on formatting issues will allow developers to quickly adjust their
habits to avoid triggering formatting errors at all.
If you want to automatically fix formatting errors and then run tests:
$ make fmt check
Benchmarking
Benchmarks serve two purposes: external integration tests (which are subject
to module visibility constraints) and actual benchmarking. To run
benchmarks, invoke make bench.
Note that link-time optimizations (LTO) are performed on the binary for benchmarking so that its performance reflects release builds that will be used in production.
The configure script will automatically detect whether the test feature
is unstable (as it was as of the time of writing) and, if so, will
automatically fall back to invoking nightly (by running cargo +nightly bench).
If you do not have nightly, run you install it via rustup install nightly.