Adding Javascript interpreter to support scoring in BigQuery. (#97)

m2cgen/__init__.py

@@ -3,11 +3,13 @@
     export_to_go,
     export_to_java,
     export_to_python,
+    export_to_javascript,
 )
 
 __all__ = [
     export_to_java,
     export_to_python,
     export_to_c,
     export_to_go,
+    export_to_javascript,
 ]

m2cgen/cli.py

@@ -23,6 +23,8 @@
         m2cgen.export_to_java, ["indent", "class_name", "package_name"]),
     "c": (m2cgen.export_to_c, ["indent"]),
     "go": (m2cgen.export_to_go, ["indent"]),
+    "javascript": (
+        m2cgen.export_to_javascript, ["indent"]),
 }
 
 

m2cgen/exporters.py

@@ -85,6 +85,25 @@ def export_to_go(model, indent=4):
     return _export(model, interpreter)
 
 
+def export_to_javascript(model, indent=4):
+    """
+    Generates a Javascript 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.
+
+    Returns
+    -------
+    code : string
+    """
+    interpreter = interpreters.JavascriptInterpreter(indent=indent)
+    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

@@ -2,11 +2,12 @@
 from .python.interpreter import PythonInterpreter
 from .c.interpreter import CInterpreter
 from .go.interpreter import GoInterpreter
-
+from .javascript.interpreter import JavascriptInterpreter
 
 __all__ = [
     JavaInterpreter,
     PythonInterpreter,
     CInterpreter,
     GoInterpreter,
+    JavascriptInterpreter,
 ]

m2cgen/interpreters/javascript/code_generator.py

@@ -0,0 +1,27 @@
+import contextlib
+
+from m2cgen.interpreters.code_generator import CLikeCodeGenerator
+
+
+class JavascriptCodeGenerator(CLikeCodeGenerator):
+    def __init__(self, *args, **kwargs):
+        super(JavascriptCodeGenerator, self).__init__(*args, **kwargs)
+
+    def add_function_def(self, name, args):
+        function_def = "function " + name + "("
+        function_def += ",".join([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):
+        self.add_function_def(name, args)
+        yield
+        self.add_block_termination()
+
+    def vector_init(self, values):
+        return "[" + ", ".join(values) + "]"
+
+    def _get_var_declare_type(self, is_vector):
+        return "var"

m2cgen/interpreters/javascript/interpreter.py

@@ -0,0 +1,50 @@
+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.javascript.code_generator \
+    import JavascriptCodeGenerator
+
+
+class JavascriptInterpreter(ToCodeInterpreter,
+                            mixins.LinearAlgebraMixin):
+
+    supported_bin_vector_ops = {
+        ast.BinNumOpType.ADD: "addVectors",
+    }
+
+    supported_bin_vector_num_ops = {
+        ast.BinNumOpType.MUL: "mulVectorNumber",
+    }
+
+    exponent_function_name = "Math.exp"
+    power_function_name = "Math.pow"
+    tanh_function_name = "Math.tanh"
+
+    def __init__(self, indent=4,
+                 *args, **kwargs):
+        self.indent = indent
+
+        cg = JavascriptCodeGenerator(indent=indent)
+        super(JavascriptInterpreter, 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="score",
+                args=args):
+            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.js")
+            self._cg.add_code_lines(utils.get_file_content(filename))
+
+        return self._cg.code

m2cgen/interpreters/javascript/linear_algebra.js

@@ -0,0 +1,19 @@
+function addVectors(v1, v2) {
+    let result = new Array(v1.length);
+
+    for (let i = 0; i < v1.length; i++) {
+        result[i] = v1[i] + v2[i];
+    }
+
+    return result;
+}
+
+function mulVectorNumber(v1, num) {
+    let result = new Array(v1.length);
+
+    for (let i = 0; i < v1.length; i++) {
+        result[i] = v1[i] * num;
+    }
+
+    return result;
+}

requirements-test.txt

@@ -8,3 +8,4 @@ pytest==4.1.1
 pytest-mock==1.10.0
 coveralls==1.5.1
 pytest-cov==2.6.1
+py-mini-racer==0.1.18

setup.py

@@ -8,7 +8,8 @@
     license="MIT",
     packages=find_packages(exclude=["tests.*", "tests"]),
     package_data={
-        "": ["linear_algebra.java", "linear_algebra.c", "linear_algebra.go"],
+        "": ["linear_algebra.java", "linear_algebra.c", "linear_algebra.go",
+             "linear_algebra.js"],
     },
     classifiers=[
         "Development Status :: 3 - Alpha",

tests/e2e/executors/__init__.py

@@ -2,10 +2,12 @@
 from tests.e2e.executors.python import PythonExecutor
 from tests.e2e.executors.c import CExecutor
 from tests.e2e.executors.go import GoExecutor
+from tests.e2e.executors.javascript import JavascriptExecutor
 
 __all__ = [
     JavaExecutor,
     PythonExecutor,
     CExecutor,
     GoExecutor,
+    JavascriptExecutor,
 ]

tests/e2e/executors/javascript.py

@@ -0,0 +1,31 @@
+import os
+from py_mini_racer import py_mini_racer
+import m2cgen as m2c
+from tests.e2e.executors import base
+
+
+class JavascriptExecutor(base.BaseExecutor):
+
+    def __init__(self, model):
+        self.model = model
+
+    def predict(self, X):
+        file_name = os.path.join(self._resource_tmp_dir, "model.js")
+
+        with open(file_name, 'r') as myfile:
+            code = myfile.read()
+
+        caller = "score([" + ",".join(map(str, X)) + "]);\n"
+
+        ctx = py_mini_racer.MiniRacer()
+        result = ctx.eval(caller + code)
+
+        return result
+
+    def prepare(self):
+        code = m2c.export_to_javascript(self.model)
+
+        file_name = os.path.join(self._resource_tmp_dir, "model.js")
+
+        with open(file_name, "w") as f:
+            f.write(code)

tests/e2e/test_e2e.py

@@ -19,6 +19,7 @@
 JAVA = pytest.mark.java
 C = pytest.mark.c
 GO = pytest.mark.go
+JAVASCRIPT = pytest.mark.javascript
 REGRESSION = pytest.mark.regr
 CLASSIFICATION = pytest.mark.clf
 
@@ -69,6 +70,7 @@ def classification_binary(model):
         (executors.JavaExecutor, JAVA),
         (executors.CExecutor, C),
         (executors.GoExecutor, GO),
+        (executors.JavascriptExecutor, JAVASCRIPT),
     ],
 
     # These models will be tested against each language specified in the