Support CelOptions to disable string conversion and list/string concatenation

[sergiitk]

Feature request checklist

• There are no issues that match the desired change
• The change is large enough it can't be addressed with a simple Pull Request
• If this is a bug, please file a Bug Report.

Change
To make CEL environment setup consistent across CEL implementations, I propose to add equivalent runtime options that control string conversion and list/string concatenation equivalent to those found in CEL-cpp:

// Enable string() overloads.
bool enable_string_conversion = true;

// Enable string concatenation overload.
bool enable_string_concat = true;

// Enable list concatenation overload.
bool enable_list_concat = true;

Example

CelCompiler CEL_COMPILER = CelCompilerFactory.standardCelCompilerBuilder()
    .setResultType(SimpleType.BOOL)
    .build();

@Test
public void cel_stringConversionDisabled() throws Exception {
  CelRuntime CEL_RUNTIME = CelRuntimeFactory.standardCelRuntimeBuilder()
      .setOptions(CelOptions.current().enableStringConversion(false).build())
      .build();

  // TODO: verify conversions to all types.
  String expr = "string(3.14) == '3.14'";
  CelRuntime.Program program = CEL_RUNTIME.createProgram(CEL_COMPILER.compile(expr).getAst());
  CelEvaluationException celErr = assertThrows(CelEvaluationException.class, program::eval);
  assertThat(celErr.getErrorCode()).isEqualTo(CelErrorCode.OVERLOAD_NOT_FOUND);
}

@Test
public void cel_stringConcatDisabled() throws Exception {
  CelRuntime CEL_RUNTIME = CelRuntimeFactory.standardCelRuntimeBuilder()
      .setOptions(CelOptions.current().enableStringConcat(false).build())
      .build();

  String expr = "'ab' + 'cd' == 'abcd'";
  CelRuntime.Program program = CEL_RUNTIME.createProgram(CEL_COMPILER.compile(expr).getAst());
  CelEvaluationException celErr = assertThrows(CelEvaluationException.class, program::eval);
  assertThat(celErr.getErrorCode()).isEqualTo(CelErrorCode.OVERLOAD_NOT_FOUND);
}

@Test
public void cel_listConcatDisabled() throws Exception {
  CelRuntime CEL_RUNTIME = CelRuntimeFactory.standardCelRuntimeBuilder()
      .setOptions(CelOptions.current().enableListConcat(false).build())
      .build();

  String expr = "size([1, 2] + [3, 4]) == 4";
  CelRuntime.Program program = CEL_RUNTIME.createProgram(CEL_COMPILER.compile(expr).getAst());
  CelEvaluationException celErr = assertThrows(CelEvaluationException.class, program::eval);
  assertThat(celErr.getErrorCode()).isEqualTo(CelErrorCode.OVERLOAD_NOT_FOUND);
}

Related

• Corresponding cel-go request: Support ProgramOptions to disable string conversion and list/string concatenation cel-go#1078
• Internal ref: go/grpc-cel-integration

[sergiitk]

FYI @TristonianJones @l46kok