README.md

Expression Evaluator

An expression evaluator with support for custom functions wrapped around a CLI.

Examples

Without a variable

go build -o ee.exe
./ee.exe -e "BAND(-(7 + 5) / 2, (7 * 5) / 2)"

With a variable via %P (if the -v flag is omitted, %P tokens fallback to a default of 1)

go build -o ee.exe
./ee.exe -e "BAND(-(%P + 5) / 2, (%P * 5) / 2)" -v 7

Supported Functions

Function	Description
NEG	NEG(X): Returns the negation of X
ABS	ABS(X): Returns the absolute value of X
ACOS	ACOS(X): Returns the arc cosine of X radians
ASIN	ASIN(X): Returns the arc sine of X radians
ATAN	ATAN(X): Returns the arc tangent of X radians
BAND	BAND(X,Y): Returns the bitwise AND of X and Y
BANDNOT	BANDNOT(X,Y): Returns the bitwise AND NOT of X and Y
BNOT	BNOT(X): Returns the bitwise NOT of X
BOR	BOR(X,Y): Returns the bitwise OR of X and Y
BXOR	BXOR(X,Y): Returns the bitwise XOR of X and Y
CEIL	CEIL(X): Returns the nearest integer greater than or equal to X
COS	COS(X): Returns the cosine of X radians
MOD	MOD(X,Y): Returns the value of X modulo Y
POW	POW(X,Y): Returns the X raised to the power of Y
RND	RND(X): Returns the integer nearest to X
SHL	SHL(X,Y): Returns the value of X shifted left by Y bits
SHR	SHR(X,Y): Returns the value of X shifted right by Y bits
SIN	SIN(X): Returns the sine of X radians
SQR	SQR(X): Returns the square root of X
TAN	TAN(X): Returns the tangent of X radians
EQ	EQ(X,Y): Returns 1 if X is equal to Y, otherwise 0
NE	NE(X,Y): Returns 1 if X is not equal to Y, otherwise 0
GE	GE(X,Y): Returns 1 if X is greater than or equal to Y, otherwise 0
GT	GT(X,Y): Returns 1 if X is greater than Y, otherwise 0
LE	LE(X,Y): Returns 1 if X is less than or equal to Y, otherwise 0
LT	LT(X,Y): Returns 1 if X is less than Y, otherwise 0
MIN	MIN(X,Y): Returns the minimum of X and Y
MAX	MAX(X,Y): Returns the maximum of X and Y
AND	AND(X,Y): Returns the logical AND of X and Y
OR	OR(X,Y): Returns the logical OR of X and Y
NOT	NOT(X): Returns the logical NOT of X

Grammar: LL(1) One token lookahead

Expression as E, Term as T, Factor as F

• Expression: E -> T { +|-|, T}
• Term: T -> F { *|/ F}
• Factor: F -> VAR | NUM | (E) | -F | FNC

Definitions:

• VAR ::= char{char}
• NUM ::= digit{digit} | digit.digit
• FNC ::= FNC(ARGS)
• ARGS ::= E {, E}