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vmware-archive / quickstep

Quickstep Project
Apache License 2.0
27 stars 13 forks source link

Add support for the substring function. #211

Closed jianqiao closed 8 years ago

jianqiao commented 8 years ago

This PR adds end-to-end support for the SUBSTRING function. Tests are also added.

TODO: In this PR, SubstringOperation is defined as a subclass of UnaryOperation. However it has two constant arguments start_position and substring_length so that it actually does not fit well into the singleton pattern as a SubstringOperation subclass. It stills remains to design a better long-term solution. For example, implement ScalarTernaryOperation or even ScalarNaryOperation class with specialization when some arguments are constants.

pateljm commented 8 years ago

LGTM. Note about is good and agree that a longer term fix is needed. Merging.

Thanks @jianqiao!