README
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bittybox | Simple floating point calculator
bittybox is a small, underpowered floating point expression evaluator.
Motivation
Performing safe, efficient user-supplied math operations.
Features
Basic operators (+-*/^), grouping, predictable operator precedence, variables, some constants and common unary functions (sin, cos, etc).
Grammar
Expr --> Unit (Binary Unit)*
Unit --> Number | "(" Expr ")" | "-" Unit | Ident
Binary --> "+" | "-" | "*" | "/" | "^"
Some Credits
Initial inspiration from the long abandoned https://github.com/marcak/calc/tree/master/
With advice from https://www.engr.mun.ca/~theo/Misc/exp_parsing.htm
Documentation
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Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type ErrInvalidSyntax ¶
ErrInvalidSyntax describes an invalid expression.
func (ErrInvalidSyntax) Error ¶
func (e ErrInvalidSyntax) Error() string
type ErrUnboundVars ¶
type ErrUnboundVars struct {
Missing []string
}
ErrUnboundVars is returned when an expression is missing variables.
func (ErrUnboundVars) Error ¶
func (e ErrUnboundVars) Error() string
type Expr ¶
type Expr struct {
// contains filtered or unexported fields
}
Expr is a compiled expression that can be reused serially.
func CompileExpr ¶
CompileExpr compiles the provided forumula into an Expr.
Example ¶
package main
import (
"fmt"
"github.com/ischneider/bittybox"
)
func main() {
expr, err := bittybox.CompileExpr("5 + y", "y")
if err != nil {
panic(err)
}
fmt.Println(expr.Evaluate([]float64{10}))
}
Output: 15
Source Files
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