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https://issues.apache.org/jira/browse/ARROW-3458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16669708#comment-16669708
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Pindikura Ravindra commented on ARROW-3458:
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> So for creating a string based expression parser can we use antlr for parser
> generation ?
yes.
> Can we have two separate implementations both in C and Java or Have an
> implementation in C and a Java binding
> for the same ?
IMO - If we do in C++ first, it'll be usable from c and python too.
> [Gandiva] Add a string based expression parser
> ----------------------------------------------
>
> Key: ARROW-3458
> URL: https://issues.apache.org/jira/browse/ARROW-3458
> Project: Apache Arrow
> Issue Type: New Feature
> Components: C++, Gandiva
> Reporter: Pindikura Ravindra
> Assignee: Praveen Krishna
> Priority: Major
> Labels: gandiva
>
> Gandiva currently supports a tree-based expression builder. This requires
> writing a lot of code for even simple expressions.
> For eg. to build an expression for "a + b < 10", the code is :
> {code:java}
> // schema for input fields
> auto field0 = field("a", int32());
> auto field1 = field("b", int32());
> auto schema = arrow::schema({field0, field1});
> // output fields
> auto field_result = field("res", boolean());
> // Build expression
> auto node_f0 = TreeExprBuilder::MakeField(field0);
> auto node_f1 = TreeExprBuilder::MakeField(field1);
> auto literal_10 = TreeExprBuilder::MakeLiteral(10);
> auto sum_expr =
> TreeExprBuilder::MakeFunction("add", {node_f0, node_f1}, int32());
> auto lt_expr =
> TreeExprBuilder::MakeExpression("less_than", {sum_expr, literal_10},
> field_result);
> {code}
> An alternate way to do this would be :
>
> {code:java}
> // Build expression
> auto expr = StringExprBuilder::MakeExpression(schema, "a + b < 10",
> field_result);
> {code}
> The expression syntax should be close to that of SQL.
>
> To begin with, this'll simplify writing tests. And, it will provide an easier
> api to work with gandiva.
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