Introduce Dart language support (#167)

.travis.yml

@@ -10,7 +10,7 @@ env:
   - TEST=API
   - TEST=E2E LANG="c_lang or python or java or go_lang or javascript or php"
   - TEST=E2E LANG="c_sharp or visual_basic or powershell"
-  - TEST=E2E LANG="r_lang"
+  - TEST=E2E LANG="r_lang or dart"
 
 before_install:
   - bash .travis/setup.sh

.travis/setup.sh

@@ -29,3 +29,11 @@ if [[ $LANG == *"php"* ]]; then
   sudo apt-get update
   sudo apt-get install --no-install-recommends -y php
 fi
+
+# Install Dart. (https://dart.dev/get-dart)
+if [[ $LANG == *"dart"* ]]; then
+  sudo sh -c 'wget -qO- https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add -'
+  sudo sh -c 'wget -qO- https://storage.googleapis.com/download.dartlang.org/linux/debian/dart_stable.list > /etc/apt/sources.list.d/dart_stable.list'
+  sudo apt-get update
+  sudo apt-get install --no-install-recommends -y dart
+fi

Dockerfile

@@ -7,6 +7,8 @@ RUN apt-get update && \
     add-apt-repository ppa:deadsnakes/ppa && \
     wget -q https://packages.microsoft.com/config/ubuntu/$(lsb_release -rs)/packages-microsoft-prod.deb -O packages-microsoft-prod.deb && \
     dpkg -i packages-microsoft-prod.deb && \
+    wget -qO- https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add - && \
+    wget -qO- https://storage.googleapis.com/download.dartlang.org/linux/debian/dart_stable.list > /etc/apt/sources.list.d/dart_stable.list && \
     apt-get update && \
     apt-get install --no-install-recommends -y \
         gcc \
@@ -20,7 +22,8 @@ RUN apt-get update && \
         dotnet-sdk-3.0 \
         powershell \
         r-base \
-        php && \
+        php \
+        dart && \
     rm -rf /var/lib/apt/lists/*
 
 WORKDIR /m2cgen

MANIFEST.in

@@ -1,5 +1,5 @@
 include LICENSE
 recursive-include m2cgen VERSION.txt
 recursive-include m2cgen linear_algebra.*
-recursive-include m2cgen tanh.bas
+recursive-include m2cgen tanh.*
 global-exclude *.py[cod]

README.md

@@ -7,7 +7,7 @@
 [![PyPI Version](https://img.shields.io/pypi/v/m2cgen.svg?logo=pypi&logoColor=white)](https://pypi.org/project/m2cgen)
 [![Downloads](https://pepy.tech/badge/m2cgen)](https://pepy.tech/project/m2cgen)
 
-**m2cgen** (Model 2 Code Generator) - is a lightweight library which provides an easy way to transpile trained statistical models into a native code (Python, C, Java, Go, JavaScript, Visual Basic, C#, PowerShell, R, PHP).
+**m2cgen** (Model 2 Code Generator) - is a lightweight library which provides an easy way to transpile trained statistical models into a native code (Python, C, Java, Go, JavaScript, Visual Basic, C#, PowerShell, R, PHP, Dart).
 
 * [Installation](#installation)
 * [Supported Languages](#supported-languages)
@@ -28,6 +28,7 @@ pip install m2cgen
 
 - C
 - C#
+- Dart
 - Go
 - Java
 - JavaScript

m2cgen/__init__.py

@@ -11,6 +11,7 @@
     export_to_powershell,
     export_to_r,
     export_to_php,
+    export_to_dart,
 )
 
 __all__ = [
@@ -24,6 +25,7 @@
     export_to_powershell,
     export_to_r,
     export_to_php,
+    export_to_dart,
 ]
 
 with open(os.path.join(os.path.dirname(os.path.realpath(__file__)),

m2cgen/cli.py

@@ -31,6 +31,7 @@
     "powershell": (m2cgen.export_to_powershell, ["indent", "function_name"]),
     "r": (m2cgen.export_to_r, ["indent", "function_name"]),
     "php": (m2cgen.export_to_php, ["indent", "function_name"]),
+    "dart": (m2cgen.export_to_dart, ["indent", "function_name"]),
 }
 
 

m2cgen/exporters.py

@@ -302,6 +302,30 @@ def export_to_php(model, indent=4, function_name="score"):
     return _export(model, interpreter)
 
 
+def export_to_dart(model, indent=4, function_name="score"):
+    """
+    Generates a Dart code representation of the given model.
+
+    Parameters
+    ----------
+    model : object
+        The model object that should be transpiled into code.
+    indent : int, optional
+        The size of indents in the generated code.
+    function_name : string, optional
+        Name of the function in the generated code.
+
+    Returns
+    -------
+    code : string
+    """
+    interpreter = interpreters.DartInterpreter(
+        indent=indent,
+        function_name=function_name,
+    )
+    return _export(model, interpreter)
+
+
 def _export(model, interpreter):
     assembler_cls = assemblers.get_assembler_cls(model)
     model_ast = assembler_cls(model).assemble()

m2cgen/interpreters/__init__.py

@@ -8,6 +8,7 @@
 from .powershell.interpreter import PowershellInterpreter
 from .r.interpreter import RInterpreter
 from .php.interpreter import PhpInterpreter
+from .dart.interpreter import DartInterpreter
 
 __all__ = [
     JavaInterpreter,
@@ -20,4 +21,5 @@
     PowershellInterpreter,
     RInterpreter,
     PhpInterpreter,
+    DartInterpreter,
 ]

m2cgen/interpreters/dart/code_generator.py

@@ -0,0 +1,40 @@
+import contextlib
+
+from m2cgen.interpreters.code_generator import CLikeCodeGenerator
+
+
+class DartCodeGenerator(CLikeCodeGenerator):
+
+    scalar_type = "double"
+    vector_type = "List<double>"
+
+    def __init__(self, *args, **kwargs):
+        super(DartCodeGenerator, self).__init__(*args, **kwargs)
+
+    def add_function_def(self, name, args, is_vector_output):
+        return_type = self._get_var_declare_type(is_vector_output)
+        function_def = return_type + " " + name + "("
+        function_def += ",".join([
+            self._get_var_declare_type(is_vector) + " " + n
+            for is_vector, n in args])
+        function_def += ") {"
+        self.add_code_line(function_def)
+        self.increase_indent()
+
+    @contextlib.contextmanager
+    def function_definition(self, name, args, is_vector_output):
+        self.add_function_def(name, args, is_vector_output)
+        yield
+        self.add_block_termination()
+
+    def vector_init(self, values):
+        return "[" + ", ".join(values) + "]"
+
+    def _get_var_declare_type(self, is_vector):
+        return (
+            self.vector_type if is_vector
+            else self.scalar_type)
+
+    def add_dependency(self, dep):
+        dep_str = "import '" + dep + "';"
+        self.prepend_code_line(dep_str)

m2cgen/interpreters/dart/interpreter.py

@@ -0,0 +1,69 @@
+import os
+
+from m2cgen import ast
+from m2cgen.interpreters import mixins
+from m2cgen.interpreters import utils
+from m2cgen.interpreters.interpreter import ToCodeInterpreter
+from m2cgen.interpreters.dart.code_generator import DartCodeGenerator
+
+
+class DartInterpreter(ToCodeInterpreter,
+                      mixins.LinearAlgebraMixin,
+                      mixins.BinExpressionDepthTrackingMixin):
+
+    supported_bin_vector_ops = {
+        ast.BinNumOpType.ADD: "addVectors",
+    }
+
+    supported_bin_vector_num_ops = {
+        ast.BinNumOpType.MUL: "mulVectorNumber",
+    }
+
+    bin_depth_threshold = 465
+
+    exponent_function_name = "exp"
+    power_function_name = "pow"
+    tanh_function_name = "tanh"
+
+    with_tanh_expr = False
+
+    def __init__(self, indent=4, function_name="score", *args, **kwargs):
+        self.indent = indent
+        self.function_name = function_name
+
+        cg = DartCodeGenerator(indent=indent)
+        super(DartInterpreter, self).__init__(cg, *args, **kwargs)
+
+    def interpret(self, expr):
+        self._cg.reset_state()
+        self._reset_reused_expr_cache()
+
+        args = [(True, self._feature_array_name)]
+
+        with self._cg.function_definition(
+                name=self.function_name,
+                args=args,
+                is_vector_output=expr.output_size > 1):
+            last_result = self._do_interpret(expr)
+            self._cg.add_return_statement(last_result)
+
+        if self.with_linear_algebra:
+            filename = os.path.join(
+                os.path.dirname(__file__), "linear_algebra.dart")
+            self._cg.add_code_lines(utils.get_file_content(filename))
+
+        # Use own tanh function in order to be compatible with Dart
+        if self.with_tanh_expr:
+            filename = os.path.join(
+                os.path.dirname(__file__), "tanh.dart")
+            self._cg.add_code_lines(utils.get_file_content(filename))
+
+        if self.with_math_module:
+            self._cg.add_dependency("dart:math")
+
+        return self._cg.code
+
+    def interpret_tanh_expr(self, expr, **kwargs):
+        self.with_tanh_expr = True
+        return super(
+            DartInterpreter, self).interpret_tanh_expr(expr, **kwargs)

m2cgen/interpreters/dart/linear_algebra.dart

@@ -0,0 +1,14 @@
+List<double> addVectors(List<double> v1, List<double> v2) {
+    List<double> result = new List<double>(v1.length);
+    for (int i = 0; i < v1.length; i++) {
+        result[i] = v1[i] + v2[i];
+    }
+    return result;
+}
+List<double> mulVectorNumber(List<double> v1, double num) {
+    List<double> result = new List<double>(v1.length);
+    for (int i = 0; i < v1.length; i++) {
+        result[i] = v1[i] * num;
+    }
+    return result;
+}

m2cgen/interpreters/dart/tanh.dart

@@ -0,0 +1,7 @@
+double tanh(double x) {
+    if (x > 22.0)
+        return 1.0;
+    if (x < -22.0)
+        return -1.0;
+    return ((exp(2*x) - 1)/(exp(2*x) + 1));
+}

tests/e2e/executors/__init__.py

@@ -8,6 +8,7 @@
 from tests.e2e.executors.powershell import PowershellExecutor
 from tests.e2e.executors.r import RExecutor
 from tests.e2e.executors.php import PhpExecutor
+from tests.e2e.executors.dart import DartExecutor
 
 __all__ = [
     JavaExecutor,
@@ -20,4 +21,5 @@
     PowershellExecutor,
     RExecutor,
     PhpExecutor,
+    DartExecutor,
 ]

tests/e2e/executors/dart.py

@@ -0,0 +1,63 @@
+import os
+import string
+
+from m2cgen import assemblers, interpreters
+from tests import utils
+from tests.e2e.executors import base
+
+EXECUTOR_CODE_TPL = """
+${model_code}
+
+void main(List<String> args) {
+    List<double> input_ = args.map((x) => double.parse(x)).toList();
+    ${print_code}
+}
+"""
+
+EXECUTE_AND_PRINT_SCALAR = """
+    double res = score(input_);
+    print(res);
+"""
+
+EXECUTE_AND_PRINT_VECTOR = """
+    List<double> res = score(input_);
+    print(res.join(" "));
+"""
+
+
+class DartExecutor(base.BaseExecutor):
+
+    executor_name = "score"
+
+    def __init__(self, model):
+        self.model = model
+        self.interpreter = interpreters.DartInterpreter()
+
+        assembler_cls = assemblers.get_assembler_cls(model)
+        self.model_ast = assembler_cls(model).assemble()
+
+        self._dart = "dart"
+
+    def predict(self, X):
+        file_name = os.path.join(self._resource_tmp_dir,
+                                 "{}.dart".format(self.executor_name))
+        exec_args = [self._dart,
+                     file_name,
+                     *map(str, X)]
+        return utils.predict_from_commandline(exec_args)
+
+    def prepare(self):
+        if self.model_ast.output_size > 1:
+            print_code = EXECUTE_AND_PRINT_VECTOR
+        else:
+            print_code = EXECUTE_AND_PRINT_SCALAR
+
+        model_code = self.interpreter.interpret(self.model_ast)
+        executor_code = string.Template(EXECUTOR_CODE_TPL).substitute(
+            model_code=model_code,
+            print_code=print_code)
+
+        executor_file_name = os.path.join(
+            self._resource_tmp_dir, "{}.dart".format(self.executor_name))
+        with open(executor_file_name, "w") as f:
+            f.write(executor_code)

tests/e2e/test_e2e.py

@@ -26,6 +26,7 @@
 POWERSHELL = pytest.mark.powershell
 R = pytest.mark.r_lang
 PHP = pytest.mark.php
+DART = pytest.mark.dart
 REGRESSION = pytest.mark.regr
 CLASSIFICATION = pytest.mark.clf
 
@@ -125,6 +126,7 @@ def classification_binary_random(model):
         (executors.PowershellExecutor, POWERSHELL),
         (executors.RExecutor, R),
         (executors.PhpExecutor, PHP),
+        (executors.DartExecutor, DART),
     ],
 
     # These models will be tested against each language specified in the