Author: Yotam Gingold
License: Public Domain. (I, Yotam Gingold, the author, release this code into the public domain.)
Homepage: http://yotamgingold.com/code/
GitHub: https://github.com/yig/miniparser
MiniParser:
A simple C++ expression parser with no external dependencies whatsoever
that can
- generate a parse tree from an expression
- parentheses
- constants
- symbolic variables
- binary operators:
- add: +
- subtract: -
- multiply: *
- divide: /
- modulus: %
- exponent: ^, **
- unary operators:
- negate: -
- functions:
- sin()
- cos()
- log() (base 10)
- ln() (base e)
- exp()
- sqrt()
- constants (override any variable with the same name):
- PI = 3.14...
NOTE: Order-of-operations is entirely left-associative. There is no
operator precedence. Use parentheses everywhere!
TODO: Operator precedence can be added easily with several lines of
find/replace in the function "Node* Parse( const std::string& str );"
See http://en.wikipedia.org/wiki/Operator-precedence_parser#Alternatives_to_Dijkstra.27s_Algorithm
example:
An example command line application that demonstrates a class
with a predefined expression evaluated via operator()
as well as an expression with an arbitrary number of variables.
Can be called with two values (x,y) or with an expression followed
by an arbitrary number of values assigned to the letters of the
alphabet (a, b, c, ...).
Version History:
- 2006-04-08:
initial release
- 2006-12-09:
added math functions (sin, cos, log, ln, exp, sqrt) and constants (PI)
improved error handling (removed an infinite loop)
- 2007-04-23:
made the grammar left associative to match natural arithmetic and C
- 2007-09-20:
added the modulus operator %. attempted to add order-of-operations,
but was foiled by unary minus (e.g. -a).