fiber/middleware/logger/template_chain.go

71 lines
2.6 KiB
Go

package logger
import (
"bytes"
"errors"
"github.com/gofiber/fiber/v2/utils"
)
// buildLogFuncChain analyzes the template and creates slices with the functions for execution and
// slices with the fixed parts of the template and the parameters
//
// fixParts contains the fixed parts of the template or parameters if a function is stored in the funcChain at this position
// funcChain contains for the parts which exist the functions for the dynamic parts
// funcChain and fixParts always have the same length and contain nil for the parts where no data is required in the chain,
// if a function exists for the part, a parameter for it can also exist in the fixParts slice
func buildLogFuncChain(cfg *Config, tagFunctions map[string]LogFunc) ([][]byte, []LogFunc, error) {
// process flow is copied from the fasttemplate flow https://github.com/valyala/fasttemplate/blob/2a2d1afadadf9715bfa19683cdaeac8347e5d9f9/template.go#L23-L62
templateB := utils.UnsafeBytes(cfg.Format)
startTagB := utils.UnsafeBytes(startTag)
endTagB := utils.UnsafeBytes(endTag)
paramSeparatorB := utils.UnsafeBytes(paramSeparator)
var fixParts [][]byte
var funcChain []LogFunc
for {
currentPos := bytes.Index(templateB, startTagB)
if currentPos < 0 {
// no starting tag found in the existing template part
break
}
// add fixed part
funcChain = append(funcChain, nil)
fixParts = append(fixParts, templateB[:currentPos])
templateB = templateB[currentPos+len(startTagB):]
currentPos = bytes.Index(templateB, endTagB)
if currentPos < 0 {
// cannot find end tag - just write it to the output.
funcChain = append(funcChain, nil)
fixParts = append(fixParts, startTagB)
break
}
// ## function block ##
// first check for tags with parameters
if index := bytes.Index(templateB[:currentPos], paramSeparatorB); index != -1 {
logFunc, ok := tagFunctions[utils.UnsafeString(templateB[:index+1])]
if !ok {
return nil, nil, errors.New("No parameter found in \"" + utils.UnsafeString(templateB[:currentPos]) + "\"")
}
funcChain = append(funcChain, logFunc)
// add param to the fixParts
fixParts = append(fixParts, templateB[index+1:currentPos])
} else if logFunc, ok := tagFunctions[utils.UnsafeString(templateB[:currentPos])]; ok {
// add functions without parameter
funcChain = append(funcChain, logFunc)
fixParts = append(fixParts, nil)
}
// ## function block end ##
// reduce the template string
templateB = templateB[currentPos+len(endTagB):]
}
// set the rest
funcChain = append(funcChain, nil)
fixParts = append(fixParts, templateB)
return fixParts, funcChain, nil
}