Content Comparison

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• https://github.com/antlr/intellij-plugin-v4 useful for testing and troubleshooting while developing grammar

PoC Code

• https://gerrit.onap.org/r/c/cps/+/121503
  (production ready!)

Findings

• Antlr4 can replace regex with less and more readable code
• Replacement of regex for CpsPathQuery fully replaced by fully compatible object generated using Antlr4 this commit: https://gerrit.onap.org/r/c/cps/+/121503
• Needed to add explicit error rule for handling unexpected tokens (otherwise Antlr would ignore them):  ErrorCharacter : . ;
• Current CPS code using regex is inconsistent and needless limited for single leave condition
• Current CPS code was lac re. @ lacking @ token for attribute names in some test cases (fixed in https://gerrit.onap.org/r/c/cps/+/121503)
• CpsPathQuerySpec did not cover all necessary possibilities (as used in some DB integration tests) This has now been addressed 
• CpsDataPersistenceQueryDataNodeSpec contains some grammar tests that should be (are already) in  CpsPathQuerySpec
• IntelliJ plugin very useful for quick testing and troubleshooting of grammar
• Not sure of best way to refresh generated code (in IntelliJ) mvn clean install in cps-path-parser seems the surest way

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