parser.go raw

   1  // Copyright 2013-2022 Frank Schroeder. All rights reserved.
   2  // Use of this source code is governed by a BSD-style
   3  // license that can be found in the LICENSE file.
   4  
   5  package properties
   6  
   7  import (
   8  	"fmt"
   9  	"runtime"
  10  )
  11  
  12  type parser struct {
  13  	lex *lexer
  14  }
  15  
  16  func parse(input string) (properties *Properties, err error) {
  17  	p := &parser{lex: lex(input)}
  18  	defer p.recover(&err)
  19  
  20  	properties = NewProperties()
  21  	key := ""
  22  	comments := []string{}
  23  
  24  	for {
  25  		token := p.expectOneOf(itemComment, itemKey, itemEOF)
  26  		switch token.typ {
  27  		case itemEOF:
  28  			goto done
  29  		case itemComment:
  30  			comments = append(comments, token.val)
  31  			continue
  32  		case itemKey:
  33  			key = token.val
  34  			if _, ok := properties.m[key]; !ok {
  35  				properties.k = append(properties.k, key)
  36  			}
  37  		}
  38  
  39  		token = p.expectOneOf(itemValue, itemEOF)
  40  		if len(comments) > 0 {
  41  			properties.c[key] = comments
  42  			comments = []string{}
  43  		}
  44  		switch token.typ {
  45  		case itemEOF:
  46  			properties.m[key] = ""
  47  			goto done
  48  		case itemValue:
  49  			properties.m[key] = token.val
  50  		}
  51  	}
  52  
  53  done:
  54  	return properties, nil
  55  }
  56  
  57  func (p *parser) errorf(format string, args ...interface{}) {
  58  	format = fmt.Sprintf("properties: Line %d: %s", p.lex.lineNumber(), format)
  59  	panic(fmt.Errorf(format, args...))
  60  }
  61  
  62  func (p *parser) expectOneOf(expected ...itemType) (token item) {
  63  	token = p.lex.nextItem()
  64  	for _, v := range expected {
  65  		if token.typ == v {
  66  			return token
  67  		}
  68  	}
  69  	p.unexpected(token)
  70  	panic("unexpected token")
  71  }
  72  
  73  func (p *parser) unexpected(token item) {
  74  	p.errorf(token.String())
  75  }
  76  
  77  // recover is the handler that turns panics into returns from the top level of Parse.
  78  func (p *parser) recover(errp *error) {
  79  	e := recover()
  80  	if e != nil {
  81  		if _, ok := e.(runtime.Error); ok {
  82  			panic(e)
  83  		}
  84  		*errp = e.(error)
  85  	}
  86  }
  87