Several refactoring and bugfix.

[odashi]

Overview

This change contains following changes:

• Fix a bug in FunctionExpander: the original implementation does not process nested functions if the outer function is retained.
• More accurate judgment to add parenthesis around functions. The new implementation tries to remove some parenthesis, e.g., $\sin (x)$ --> $\sin x$.
• Adjusts old codegen rules around tuple/list/set.
• Simplifying some tests, and providing more exhaustive tests.
• Some small refactoring.

Details

New features added by this change is follows:

• FunctionRule dataclass, representing a codegen rule of a builtin function.
• Defines the default precedence of ast.Call as a value just above unary operators so that unary operators are wrapped by parentheses:
  • sin(x) --> $\sin x$
  • sin(-x) --> $\sin (-x)$
  • -sin(-x) --> $- \sin x$
• Factorial ( $x!$ ) is the special case of this rule: if either the function or argument is a factorial, it is always wrapped by parentheses to avoid confusion:
  • sin(factorial(x)) --> $\sin (x!)$
  • factorial(sin(x)) --> $(\sin x)!$
  • factorial(factorial(x)) --> $(x!)!$

References

• NA

Blocked by

• Adds parse_expr utility #144