Update of the typer with shifts and assignments

[AaronGhost]

Updates the Typer class to produce a result in the case of assignments
and the TyperHelper class to correctly type shift operations in the
case of left and right scalar types (the resulting type is the one
from the left operand).

[afd]

Thanks for spotting this discrepancy!

Please add a test along these lines to TyperTest, right after testLengthTyped:

  @Test
  public void testLengthTyped() throws Exception {
    final TranslationUnit tu = ParseHelper.parse("#version 320 es\n"
        + "void main() {\n"
        + "  int a;\n"
        + "  uint b;\n"
        + "  ivec2 av;\n"
        + "  uvec2 bv;\n"
        + "\n"
        + "  int x0 = a << a;\n"
        + "  int x1 = a << b;\n"
        + "  uint x2 = b << a;\n"
        + "  uint x3 = b << b;\n"
        + "  ivec2 x4 = av << a;\n"
        + "  ivec2 x5 = av << b;\n"
        + "  ivec2 x6 = av << av;\n"
        + "  ivec2 x7 = av << bv;\n"
        + "  uvec2 x8 = bv << a;\n"
        + "  uvec2 x9 = bv << b;\n"
        + "  uvec2 x10 = bv << av;\n"
        + "  uvec2 x11 = bv << bv;\n"
        + "}\n");
    new NullCheckTyper(tu) {
      private int counter = 0;
      @Override
      public void visitBinaryExpr(BinaryExpr binaryExpr) {
        super.visitBinaryExpr(binaryExpr);
        if (binaryExpr.getOp() == BinOp.LEFT_SHIFT) {
          switch(counter) {
            case 0:
            case 1:
            assertSame(BasicType.INT, lookupType(binaryExpr));
            break;
            case 2:
            case 3:
            assertSame(BasicType.UINT, lookupType(binaryExpr));
            break;
            case 4:
            case 5:
            case 6:
            case 7:
            assertSame(BasicType.IVEC2, lookupType(binaryExpr));
            break;
            case 8:
            case 9:
            case 10:
            case 11:
            assertSame(BasicType.UVEC2, lookupType(binaryExpr));
            break;
            defalt:
            fail();
          }
          counter++;
        }
      }
    }.visit(tu);
  }

It's probably syntactically incorrect but hopefully you get the gist and can fix it up (and fix your code to make it pass, if needed).

And can you adapt its name suitably for the << operator, and add an analogous test for the >> operator?

Plus there's one comment in the review about a comment.

[AaronGhost]

Done!

[afd]

LGTM.