[toml] Implement a TOML parser as package tomlmojo and use it to re-factor tests (#63)

This pull request includes several changes to improve the testing and
packaging of the `decimojo` and `tomlmojo` libraries. The most important
changes involve implementing a TOML parser in package `tomlmojo`,
restructuring the test cases to load from a TOML file, adding new test
cases, and updating the packaging commands.

Improvements to testing:

*
[`tests/biguint/test_biguint_arithmetics.mojo`](diffhunk://#diff-855e834af415ace9cb8340506c824c86a99bed282917f2d90075705170195827R7-R52):
Refactored the test functions (`test_add`, `test_subtract`,
`test_multiply`, `test_extreme_cases`) to load test cases from a TOML
file and added structured `TestCase` for better test management.
[[1]](diffhunk://#diff-855e834af415ace9cb8340506c824c86a99bed282917f2d90075705170195827R7-R52)
[[2]](diffhunk://#diff-855e834af415ace9cb8340506c824c86a99bed282917f2d90075705170195827L81-L132)
[[3]](diffhunk://#diff-855e834af415ace9cb8340506c824c86a99bed282917f2d90075705170195827L142-R108)
[[4]](diffhunk://#diff-855e834af415ace9cb8340506c824c86a99bed282917f2d90075705170195827L185-R163)
*
[`src/decimojo/tests.mojo`](diffhunk://#diff-2111591ff6c3243ac0d5ada070d08238c8c1b15e419da7ecc99fd680917252c4R1-R55):
Added a new file to implement `TestCase` struct and functions for
managing test cases.
*
[`tests/biguint/test_data/biguint_arithmetics.toml`](diffhunk://#diff-54c73fb8f7a46321f65b4c3080f874518363de06347f935a232028de46ebd7feR1-R160):
Added a new TOML file to hold test data for BigUInt arithmetic
operations, including addition, subtraction, multiplication, and extreme
cases.

Packaging updates:

*
[`mojoproject.toml`](diffhunk://#diff-1b0ef62120bccf4c05a76e60e13fe686f33eb92d5897b3f05e0c3f8d737fc5c0L20-R26):
Updated the packaging commands to include separate packaging for
`decimojo` and `tomlmojo` libraries and updated the clean command to
remove additional files.

Licensing and documentation:

*
[`src/decimojo/__init__.mojo`](diffhunk://#diff-6499d0e8dbd5799013a6c0d8a5539d86b3d7d1d32ee6983f110d14ca0b4d06ffL2-L4):
Removed redundant comments and updated the file header.
*
[`src/tomlmojo/__init__.mojo`](diffhunk://#diff-d640b9adf5ccc6ab3c2585fae60a6598e1f6d6a9130949bc48e73ab7eaaae77fR1-R21):
Added a new file with licensing information and initial import
statements for TOML parsing.

Author: forfudan

.github/workflows/run_tests.yaml

@@ -52,8 +52,10 @@ jobs:
       - name: Build package
         run: |
           magic run mojo package src/decimojo
+          magic run mojo package src/tomlmojo
           cp decimojo.mojopkg tests/
           cp decimojo.mojopkg benches/
+          mv tomlmojo.mojopkg tests/
 
       - name: Run tests
         run: |

README.md

@@ -15,6 +15,8 @@ The core types are:
 
 The library is expanding to include `BigDecimal` types that support arbitrary precision[^arbitrary], allowing for calculations with unlimited digits and decimal places. These extensions are currently under active development.
 
+This repository includes [TOMLMojo](https://github.com/forfudan/decimojo/tree/main/src/tomlmojo), a lightweight TOML parser in pure Mojo. It parses configuration files and test data, supporting basic types, arrays, and nested tables. While created for DeciMojo's testing framework, it offers general-purpose structured data parsing with a clean, simple API.
+
 ## Installation
 
 DeciMojo is available in the [modular-community](https://repo.prefix.dev/modular-community) package repository. You can install it using any of these methods:

mojoproject.toml

@@ -17,11 +17,14 @@ max = ">=25.2"
 format = "magic run mojo format ./"
 
 # compile the package
-package = "magic run format && magic run mojo package src/decimojo && cp decimojo.mojopkg tests/ && cp decimojo.mojopkg benches/ && rm decimojo.mojopkg"
+package_decimojo = "magic run mojo package src/decimojo && cp decimojo.mojopkg tests/ && cp decimojo.mojopkg benches/ && rm decimojo.mojopkg"
+package_tomlmojo = "magic run mojo package src/tomlmojo && mv tomlmojo.mojopkg tests/"
+package = "magic run format && magic run package_decimojo && magic run package_tomlmojo"
 p = "clear && magic run package"
 
 # clean the package files in tests folder
-clean = "rm tests/decimojo.mojopkg && rm benches/decimojo.mojopkg"
+clean = "rm tests/decimojo.mojopkg && rm benches/decimojo.mojopkg && rm tests/tomlmojo.mojopkg"
+c = "clear && magic run clean"
 
 # tests (use the mojo testing tool)
 test = "magic run package && magic run mojo test tests --filter"

src/decimojo/__init__.mojo

@@ -1,7 +1,4 @@
 # ===----------------------------------------------------------------------=== #
-# DeciMojo: A fixed-point decimal arithmetic library in Mojo
-# https://github.com/forfudan/decimojo
-#
 # Copyright 2025 Yuhao Zhu
 #
 # Licensed under the Apache License, Version 2.0 (the "License");

src/decimojo/tests.mojo

@@ -0,0 +1,55 @@
+# ===----------------------------------------------------------------------=== #
+# Copyright 2025 Yuhao Zhu
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ===----------------------------------------------------------------------=== #
+
+"""
+Implement structs and functions for tests.
+"""
+
+
+struct TestCase:
+    """Structure to hold test case data.
+
+    Attributes:
+        a: The first input value as numeric string.
+        b: The second input value as numeric string.
+        expected: The expected output value as numeric string.
+        description: A description of the test case.
+    """
+
+    var a: String
+    var b: String
+    var expected: String
+    var description: String
+
+    fn __init__(
+        out self, a: String, b: String, expected: String, description: String
+    ):
+        self.a = a
+        self.b = b
+        self.expected = expected
+        self.description = description + "\nx1 = " + self.a + "\nx2 = " + self.b
+
+    fn __copyinit__(out self, other: Self):
+        self.a = other.a
+        self.b = other.b
+        self.expected = other.expected
+        self.description = other.description
+
+    fn __moveinit__(out self, owned other: Self):
+        self.a = other.a^
+        self.b = other.b^
+        self.expected = other.expected^
+        self.description = other.description^

src/tomlmojo/__init__.mojo

@@ -0,0 +1,21 @@
+# ===----------------------------------------------------------------------=== #
+# Copyright 2025 Yuhao Zhu
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ===----------------------------------------------------------------------=== #
+
+"""
+A simple TOML parser for Mojo.
+"""
+
+from .parser import parse_file, TOMLValueType