Hi everyone,
I'm trying out Dland, always been and have been a big fan. So to
give it a good run i wanted to create is a java class parser,
based on the spec released here. (
https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html.)
The class file can be represented in the following "struct" like:
ClassFile {
u4 magic;
u2 minor_version;
u2 major_version;
u2 constant_pool_count;
cp_info constant_pool[constant_pool_count-1];
u2 access_flags;
u2 this_class;
u2 super_class;
u2 interfaces_count;
u2 interfaces[interfaces_count];
u2 fields_count;
field_info fields[fields_count];
u2 methods_count;
method_info methods[methods_count];
u2 attributes_count;
attribute_info attributes[attributes_count];
}
where:
u4 == ubyte[4] --> integer
u2 == ubyte[2] --> short
u1 == ubyte[1] --> byte
I have the first 4 fields parsing, however i stumble upon an
example where you can use a rawRead() with a struct, therefore
representing the entire structure and then reading from rawRead()
like
````d
ClassFile[1] classFileStruct;
f.rawRead(claddFileStruct);
````
Unfortunately the struct doesn't know at compile time what the
size of the constant_pool array, or at-least was not able to
specify it dynamically.
What is the best approach to go about parsing such structure?
Should i have structs to represent the blocks of fixed fields
from the structure and then parsing each variable (length)
structure manually?
Something like this?
````
ClassHeader[1] classHeader;
f.rawRead(classHeader);
CpInfo[] cpInfo = new CpInfo[classHeader.constant_pool_count];
f.rawRead(cpInfo);
`````
Really appreciate any knowledgeable suggestions.
Regards
Ade
