efp

README

EFP (Excel Formula Parser)

Using EFP (Excel Formula Parser) you can get an Abstract Syntax Tree (AST) from Excel formula.

Installation

go get github.com/xuri/efp

Example

package main

import "github.com/xuri/efp"

func main() {
    ps := efp.ExcelParser()
    ps.Parse("=SUM(A3+B9*2)/2")
    println(ps.PrettyPrint())
}

Get AST

SUM <Function> <Start>
    A3 <Operand> <Range>
    + <OperatorInfix> <Math>
    B9 <Operand> <Range>
    * <OperatorInfix> <Math>
    2 <Operand> <Number>
 <Function> <Stop>
/ <OperatorInfix> <Math>
2 <Operand> <Number>

Contributing

Contributions are welcome! Open a pull request to fix a bug, or open an issue to discuss a new feature or change.

Credits

EFP (Excel Formula Parser) is a Go language port of E. W. Bachtal's Excel formula parser.

Licenses

This program is under the terms of the BSD 3-Clause License. See https://opensource.org/licenses/BSD-3-Clause.

Documentation

Overview

Package efp (Excel Formula Parser) tokenize an Excel formula using an implementation of E. W. Bachtal's algorithm.

Go language version by Ri Xu: https://xuri.me

Index

• Constants
• type Parser
  • func ExcelParser() Parser
  • func (ps *Parser) EOF() bool
  • func (ps *Parser) Parse(formula string) []Token
  • func (ps *Parser) PrettyPrint() string
  • func (ps *Parser) Render() string
• type Token
• type Tokens
  • func (tk *Tokens) BOF() bool
  • func (tk *Tokens) EOF() bool

Constants

const (
	// Character constants
	QuoteDouble  = '"'
	QuoteSingle  = '\''
	BracketClose = ']'
	BracketOpen  = '['
	BraceOpen    = '{'
	BraceClose   = '}'
	ParenOpen    = '('
	ParenClose   = ')'
	Semicolon    = ';'
	Whitespace   = ' '
	Comma        = ','
	ErrorStart   = '#'

	OperatorsSN      = "+-"
	OperatorsInfix   = "+-*/^&=><"
	OperatorsPostfix = '%'

	// Token type
	TokenTypeNoop            = "Noop"
	TokenTypeOperand         = "Operand"
	TokenTypeFunction        = "Function"
	TokenTypeSubexpression   = "Subexpression"
	TokenTypeArgument        = "Argument"
	TokenTypeOperatorPrefix  = "OperatorPrefix"
	TokenTypeOperatorInfix   = "OperatorInfix"
	TokenTypeOperatorPostfix = "OperatorPostfix"
	TokenTypeWhitespace      = "Whitespace"
	TokenTypeUnknown         = "Unknown"

	// Token subtypes
	TokenSubTypeStart         = "Start"
	TokenSubTypeStop          = "Stop"
	TokenSubTypeText          = "Text"
	TokenSubTypeNumber        = "Number"
	TokenSubTypeLogical       = "Logical"
	TokenSubTypeError         = "Error"
	TokenSubTypeRange         = "Range"
	TokenSubTypeMath          = "Math"
	TokenSubTypeConcatenation = "Concatenation"
	TokenSubTypeIntersection  = "Intersection"
	TokenSubTypeUnion         = "Union"
)

QuoteDouble, QuoteSingle and other's constants are token definitions.

Types

type Parser

type Parser struct {
	Formula string

	Tokens     Tokens
	TokenStack Tokens
	Offset     int
	InString   bool
	InPath     bool
	InRange    bool
	InError    bool
	// contains filtered or unexported fields
}

Parser inheritable container. TokenStack directly maps a LIFO stack of tokens.

func ExcelParser

func ExcelParser() Parser

ExcelParser provides function to parse an Excel formula into a stream of tokens.

func (*Parser) EOF

func (ps *Parser) EOF() bool

EOF provides function to check whether end of tokens stack.

func (*Parser) Parse

func (ps *Parser) Parse(formula string) []Token

Parse provides function to parse formula as a token stream (list).

func (*Parser) PrettyPrint

func (ps *Parser) PrettyPrint() string

PrettyPrint provides function to pretty the parsed result with the indented format.

func (*Parser) Render

func (ps *Parser) Render() string

Render provides function to get formatted formula after parsed.

type Token

type Token struct {
	TValue   string
	TType    string
	TSubType string
}

Token encapsulate a formula token.

type Tokens

type Tokens struct {
	Index int
	Items []Token
}

Tokens directly maps the ordered list of tokens. Attributes:

items - Ordered list
index - Current position in the list

func (*Tokens) BOF

func (tk *Tokens) BOF() bool

BOF provides function to check whether beginning of list.

func (*Tokens) EOF

func (tk *Tokens) EOF() bool

EOF provides function to check whether end of list.