Parsing a string as a line of code in C ++
Is it possible that a string variable can be parsed as an actual line of code in C ++? For example, can this string be "x=0"
parsed as valid code and set the value x
(some random variable in the program) to zero? What I plan to do with this is what I want to make a simple C ++ plotter. The user enters a function (the function will be in terms of x
and y
and will have a value of 0) to be constructed as a string (for example 2*y+x
), which will then be converted to a code object and then accordingly using a loop.
Since C ++ is a compiled and linked language, it is not suitable for on-the-fly evaluation.
But in the past I've achieved something similar to your goals with C ++ embedding a Python interpreter to evaluate Python code as strings on the fly and pipe the results to C ++ code.
Some other popular scripting languages that can be embedded into a C ++ program are Lua and Squirrel .
In Java, I did the same by introducing the Groovy interpreter .
You need to integrate the scripting interpreter into your code by nesting it, and then pass the values from the scripting language code to your C ++ code using the sorting process .
If you really want C ++ syntax that can be interpreted, it is theoretically possible to develop a dynamic parser and interpreter for a subset of the language, but C ++ is a complex language, and such a task would be a huge task fraught with difficulties and mostly a use case for the wrong tool for work.
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The short answer is no. You cannot compile C / C ++ on the fly like this, as it is a compiled language, not an interpreted one.
But here's the idea: you can inline a JavaScript interpreter using the SpiderMonkey API , which can interpret all of your example code snippets, as JavaScript syntax is very similar to C / C ++ in that respect.
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The short answer is yes. Compiling C ++ on the fly works fine using C ++ JIT. From llvm.org
A Just-In-Time (JIT) code generation system that currently supports X86, X86-64, ARM, AArch64, Mips, SystemZ, PowerPC, and PowerPC-64.
It assumes that you are willing to link most of the compiler in your program to achieve this. With a concerted effort, you should be able to write "eval" on top of your existing API.
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