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Add parsing options, including option to skip automatic date parsing #87

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Add parsing options, including option to skip automatic date parsing #87

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31 changes: 29 additions & 2 deletions EvaluableExpression.go
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,32 @@ type EvaluableExpression struct {
inputExpression string
}

// An Option is used to define the behavior of the expression parser.
type Option func(*options)

type options struct {
skipDateParsing bool
}

func getOpts(o ...Option) (res options) {
for _, f := range o {
f(&res)
}
return
}

var (
// The SkipDateParsing disables the automatic attempt to parse strings as dates.
// By default, date parsing is automatically tried with any string constant
SkipDateParsing Option = skipDateParsing
)

var (
skipDateParsing = func(o *options) {
o.skipDateParsing = true
}
)

/*
Parses a new EvaluableExpression from the given [expression] string.
Returns an error if the given expression has invalid syntax.
Expand Down Expand Up @@ -87,16 +113,17 @@ func NewEvaluableExpressionFromTokens(tokens []ExpressionToken) (*EvaluableExpre
Similar to [NewEvaluableExpression], except enables the use of user-defined functions.
Functions passed into this will be available to the expression.
*/
func NewEvaluableExpressionWithFunctions(expression string, functions map[string]ExpressionFunction) (*EvaluableExpression, error) {
func NewEvaluableExpressionWithFunctions(expression string, functions map[string]ExpressionFunction, opts ...Option) (*EvaluableExpression, error) {

var ret *EvaluableExpression
var err error

o := getOpts(opts...)
ret = new(EvaluableExpression)
ret.QueryDateFormat = isoDateFormat
ret.inputExpression = expression

ret.tokens, err = parseTokens(expression, functions)
ret.tokens, err = parseTokens(expression, functions, o)
if err != nil {
return nil, err
}
Expand Down
19 changes: 10 additions & 9 deletions parsing.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ import (
"unicode"
)

func parseTokens(expression string, functions map[string]ExpressionFunction) ([]ExpressionToken, error) {
func parseTokens(expression string, functions map[string]ExpressionFunction, opts options) ([]ExpressionToken, error) {

var ret []ExpressionToken
var token ExpressionToken
Expand All @@ -25,7 +25,7 @@ func parseTokens(expression string, functions map[string]ExpressionFunction) ([]

for stream.canRead() {

token, err, found = readToken(stream, state, functions)
token, err, found = readToken(stream, state, functions, opts)

if err != nil {
return ret, err
Expand All @@ -52,7 +52,7 @@ func parseTokens(expression string, functions map[string]ExpressionFunction) ([]
return ret, nil
}

func readToken(stream *lexerStream, state lexerState, functions map[string]ExpressionFunction) (ExpressionToken, error, bool) {
func readToken(stream *lexerStream, state lexerState, functions map[string]ExpressionFunction, opts options) (ExpressionToken, error, bool) {

var function ExpressionFunction
var ret ExpressionToken
Expand Down Expand Up @@ -214,12 +214,13 @@ func readToken(stream *lexerStream, state lexerState, functions map[string]Expre
stream.rewind(-1)

// check to see if this can be parsed as a time.
tokenTime, found = tryParseTime(tokenValue.(string))
if found {
kind = TIME
tokenValue = tokenTime
} else {
kind = STRING
kind = STRING
if !opts.skipDateParsing {
tokenTime, found = tryParseTime(tokenValue.(string))
if found {
kind = TIME
tokenValue = tokenTime
}
}
break
}
Expand Down