Regex verursacht Stackoverflow

Question

Ich habe folgende regexp

(([^'])|(''))* 

, die die Literale gut genug, um in der Regel

aber mit dem folgenden Text zu analysieren (Sie können es versuchen):

xxxxxxx_xxx_xxxxxxx=xxxxxx.xxxxxxxxxxx.xxxxxxx.xxxxxxxxxx`2[xxxxxx.xxxxxx,xxxxxx.xxxxxx]xxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxxxxxxxxxx=1455544499467&xxxxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xx=xxxxxxx &xxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxx=xxxxxxx_701454xx-x23x-4x31-xx75-xxx185x3xx26&xxxxxx_xxxxxxxx_xxx_xxxxxxxxxx=xxxxx&xxxxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxxx=xxxxxxx&xxxxxxxx_xxx_xx=xxxxxxx_2x542x7x-7x94-4867-8819-239x732xx3x1&xxxxxxxxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxxxxxxxx=xxxxx&xxxxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxxxxxxx=xx-xx&xxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxx=7&xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxxxxxx=xxx2012x2xx.xxx.xxx:82&xxxxxxx_xxxxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxx=11.0&xxxxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxx=xxxx&xxxxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxxxxx=xxxxxxxxx&xx_xxxxxxxxx_xxxxxxxxxxxxxxxx_xxxxxxxxxxx_xxxxx_xxx_xxxxxxx=xx 6.3&xxxxxxxxxxx_xxxxx_xxx_xxxxxxxxxxxxxxxxxxx=<xxxxxxx-xxxxx xxxxx="xxx">xxxxxx xxxxxx"></xxxxxxx><xxxxxxx-xxxx xxx-xxxxx="xx_xxxx" xxxxxxxx="xxxx" xxxx="xxxxxxxxxxx xxxx"><xxxx-xx-xxxxxx xxxxxxxxxxx="xxxx"><xxxxx>xxxxxxxxxx</xxxxx><xxxxx>xxxxx</xxxxx><xxxxx>xxx</xxxxx><xxxxx>xxxxxxxxx</xxxxx><xxxxx>xxxxxxx</xxxxx></xxxx-xx-xxxxxx></xxxxxxx-xxxx><xxxxxxx-xxxx xxx-xxxxx="xx_xxxxxxxx" xxxxxxxx="xxxxxxxx" xxxx="xx_xxxxxxxx"/><xxxxxxx-xxxx xxx-xxxxx="xx_xx_xxxxx" xxxxxxxx="xxxx" xxxx="xxxxxxx - xxxxxx xxxxxx?"><xxxx-xx-xxxxxx xxxxxxxxxxx="xxxxx"> 2</xxxxx></xxxx-xx-xxxxxx><xxxxx>xxxx</xxxxx><xxxxx>xxxxx</xxxxx></xxxx-xx-xxxxxx></xxxxxxx-xxxx><xxxxxxx-xxxx xxx-xxxxx="xx_xxxx_xxxx" xxxxxxxx="xxxx" xxxx="xx_xxxx_xxxx"></xxxxxxx><xxxxxxx-xxxx xxx-xxxxx="xx_xxxxxxx" xxxxxxxx="xxxxxx" xxxx="xx_xxxxxxx"></xxxxxxx><xxxxxxx-xxxx xxx-xxxxx="xx_xx_xxxxxxxxxxxxxx_xxxxxx" xxxxxxxx="xxxx"xxxx="xxxxxxx - xxxxxxxxxxxxxx xxxxxx"></xxxxxxx><xxxxxxx-xxxx xxx-xxxxx="xx_xxxxxx" xxxxxxxx="xxxx" xxxx="xxxxxxxxxxx xxxxxx">') 

Ich bekomme StackOverflowError:

Exception in thread "main" java.lang.StackOverflowError 
    at java.util.regex.Pattern$Branch.match(Pattern.java:4600) 
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658) 
    at java.util.regex.Pattern$Loop.match(Pattern.java:4785) 
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717) 
    at java.util.regex.Pattern$BranchConn.match(Pattern.java:4568) 
    at java.util.regex.Pattern$GroupTail.match(Pattern.java:4717) 
    at java.util.regex.Pattern$CharProperty.match(Pattern.java:3777) 
    at java.util.regex.Pattern$GroupHead.match(Pattern.java:4658) 

Was könnte das Problem sein? Ist eine solche Ausnahme wegen zu langer Länge der Zeichenfolge (2030 Symbole) möglich? Oder habe ich hier spezielle Symbole, die diese Fehler verursachen?

Irgendwelche Gedanken

Answer 1

Zunächst einmal geschätzt, man die inneren Aufnahmegruppen nicht benötigen. Wiederholte Erfassungsgruppen erfassen nur das letzte Vorkommen, daher sind sie in Java nutzlos.

Als nächstes können Sie diese Regex unroll so dass es linear entspricht (ohne Wechsel, die eine Menge von Ressourcen frisst):

[^']*(?:''[^']*)* 

die updated regex Demo ansehen.

Muster Details:

• [^']* - entspricht null oder mehr Zeichen andere als '
• (?:''[^']*)* - entspricht null oder mehrere Sequenzen von:
  • '' - zwei Einzel Apostrophe
  • [^']* - null oder mehr Zeichen außer '