AST parser does not support left and right function.

[samuelhsin]

I try to write left or right function，and use parser to get ast tree. But parser returns error. I think these function names are confused by "left join" and "right join".

-- SQL
SELECT left('w3resource',3)
AS "Extract 3 characters from the left";

Error:

SELECT left
^
Unexpected kw_left token: "left". Instead, I was expecting to see one of the following:

- A "kw_all" token
- A "kw_distinct" token
- A "kw_from" token
- A "star" token
- A "lparen" token
- A "kw_where" token
- A "kw_group" token
- A "kw_order" token
- A "kw_for" token
- A "kw_not" token
- A "kw_offset" token
- A "kw_limit" token
- A "kw_fetch" token
- A "kw_union" token
- A "semicolon" token
- A "word" token
- A "op_plus" token
- A "op_minus" token
- A "kw_cast" token
- A "kw_current_schema" token
- A "kw_current_schema" token
- A "kw_true" token
- A "kw_false" token
- A "kw_null" token
- A "qparam" token
- A "kw_default" token
- A "word" token
- A "word" token
- A "word" token
- A "word" token
- A "kw_precision" token
- A "kw_array" token
- A "kw_array" token
- A "kw_case" token
- A "kw_primary" token
- A "kw_unique" token
- A "quoted_word" token
- A "word" token
- A "float" token
- A "int" token
- A "kw_current_catalog" token
- A "kw_current_date" token
- A "kw_current_role" token
- A "kw_current_schema" token
- A "kw_current_timestamp" token
- A "kw_current_time" token
- A "kw_localtimestamp" token
- A "kw_localtime" token
- A "kw_session_user" token
- A "kw_user" token
- A "kw_current_user" token
- A "string" token
- A "eString" token
- A "kw_any" token
- A "kw_some" token
- A "kw_all" token


at Parser.feed (nearley.js?b104:343:1)
at _parse (index.js?3b70:1909:1)
at doParse (index.js?3b70:1864:1)

https://www.w3resource.com/PostgreSQL/left-function.php
https://www.w3resource.com/PostgreSQL/right-function.php