CodeGenerator parses size expressions incorrectly (wrong values and thrown exceptions)

[ff-meli]

The latest cimgui (master, hash be187bcdc43b124250f7c0f6b4c216a4094053b1) generates successfully, but CodeGenerator in ImGui.NET cannot process the output.

In structs_and_enums.json, under ImFont is the item:

{
    "name": "Used4kPagesMap[(0xFFFF+1)/4096/8]",
    "size": 2,
    "type": "ImU8"
}

This fails to parse and throws here:

CodeGenerator.dll!CodeGenerator.TypeReference.ParseSizeString(string sizePart, CodeGenerator.EnumDefinition[] enums) Line 1182
CodeGenerator.dll!CodeGenerator.TypeReference.TypeReference(string name, string type, string templateType, CodeGenerator.EnumDefinition[] enums, string[] typeVariants) Line 1164
CodeGenerator.dll!CodeGenerator.TypeReference.TypeReference(string name, string type, string templateType, CodeGenerator.EnumDefinition[] enums) Line 1138
CodeGenerator.dll!CodeGenerator.Program.Main.AnonymousMethod__7(Newtonsoft.Json.Linq.JToken v) Line 173

I'll look at this a bit, but I am unfamiliar with cimgui's formatting or how CodeGenerator processes it, so I may not be able to address this correctly.

[ff-meli]

The actual definition in imgui is ImU8 Used4kPagesMap[(IM_UNICODE_CODEPOINT_MAX+1)/4096/8]; so I can see where that is coming from, though I'm not sure if is an ImGui.NET bug, or something that cimgui should be expected to resolve

[ff-meli]

Actually in quick debugging, other values parse incorrectly here as well, though they don't appear to throw. "ArcFastVtx[12*1]" evaluates its size to -1.

It seems like this needs more robust expression parsing.

[ff-meli]

I was able to hack around this to make the generator 'succeed', basically just using a regex to turn hex->decimal in the string and then using ncalc instead of the existing parse logic (ncalc seemingly cannot handle hex)

I also wasn't sure why it parses the size at all, since in cases where it is an expression, the result seems to be included in the json as a 'size' field, but I left this behavior in since I assumed there must be a reason for it.

However, there are a lot of other issues with the current cimgui that the generator just does not handle. I'll put those in a separate issue.

[sonoro1234]

"ArcFastVtx[12*1]" evaluates its size to -1.

It seems like this needs more robust expression parsing.

This dont needs to be parsed, just take size field (and discard [xxx] in name)

{
        "name": "ArcFastVtx[12*1]",
        "size": 12,
        "type": "ImVec2"
      },