Fix infinite loop generated from repeating structure

[pei0804]

for #88

[codecov-io]

Codecov Report

Merging #92 into master will increase coverage by 0.21%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #92      +/-   ##
==========================================
+ Coverage   85.61%   85.82%   +0.21%     
==========================================
  Files           5        5              
  Lines         737      748      +11     
==========================================
+ Hits          631      642      +11     
  Misses         65       65              
  Partials       41       41

Impacted Files	Coverage Δ
parser.go	81.62% <100%> (+0.56%)	⬆️

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[easonlin404]

LGTM