Escape character support for string literals

[MitchellGale]

Description

Adds support for escape characters \ to be used to escape characters in string literals. Keeps support for double quote to act as an escape if the surrounding quote is matching type (single quote, or double quote).

SELECT "Hello", 'Hello', "It""s", 'It''s', "It's", '"Its"', 'It\'s', 'It\\\'s', "\I\t\s"
fetched rows / total rows = 1/1
+-----------+-----------+-----------+-----------+----------+-----------+-----------+-------------+------------+
| "Hello"   | 'Hello'   | "It""s"   | 'It''s'   | "It's"   | '"Its"'   | 'It\'s'   | 'It\\\'s'   | "\I\t\s"   |
|-----------+-----------+-----------+-----------+----------+-----------+-----------+-------------+------------|
| Hello     | Hello     | It"s      | It's      | It's     | "Its"     | It's      | It\'s       | \I\t\s     |
+-----------+-----------+-----------+-----------+----------+-----------+-----------+-------------+------------+

Issues Resolved

#297

Check List

• New functionality includes testing.
  • All tests pass, including unit test, integration test and doctest
• New functionality has been documented.
  • New functionality has javadoc added
  • New functionality has user manual doc added
• Commits are signed per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov-commenter]

Codecov Report

Merging #1206 (16de714) into main (18661b4) will decrease coverage by 2.48%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               main    #1206      +/-   ##
============================================
- Coverage     98.32%   95.83%   -2.49%     
  Complexity     3552     3552              
============================================
  Files           346      356      +10     
  Lines          8756     9414     +658     
  Branches        554      673     +119     
============================================
+ Hits           8609     9022     +413     
- Misses          142      334     +192     
- Partials          5       58      +53     

Flag	Coverage Δ
query-workbench	62.76% <ø> (?)
sql-engine	98.32% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
workbench/public/components/PPLPage/PPLPage.tsx	56.52% <0.00%> (ø)
workbench/public/components/SQLPage/SQLPage.tsx	100.00% <0.00%> (ø)
workbench/public/utils/PanelWrapper.tsx	100.00% <0.00%> (ø)
workbench/public/application.tsx	0.00% <0.00%> (ø)
workbench/public/components/Main/main.tsx	53.00% <0.00%> (ø)
workbench/public/components/Header/Header.tsx	100.00% <0.00%> (ø)
...ublic/components/QueryResults/QueryResultsBody.tsx	68.32% <0.00%> (ø)
...ch/public/components/QueryResults/QueryResults.tsx	61.60% <0.00%> (ø)
...h/public/components/QueryLanguageSwitch/Switch.tsx	85.71% <0.00%> (ø)
workbench/public/components/app.tsx	0.00% <0.00%> (ø)

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[Yury-Fridlyand]

Isn't a breaking change?

[acarbonetto]

Isn't a breaking change?

Yes. This should not be a backport change.

[penghuo]

could you add more context about breacking change in PR. then during release stage, we can organice all the breaking changes in release notes.

[Yury-Fridlyand]

1. Add a test index:

curl -X POST "localhost:9200/dbg/_doc/?pretty" -H 'Content-Type: application/json' -d '{"someText": "\\1\\\\2\\\\\\3\\\\\\\\4\\\\\\\\\\5\\\\\\\\\\\\6"}'

(actually there are 1..6 backslashes, but they are escaped)

2. Run a query (without this fix):

opensearchsql> select * from dbg;
fetched rows / total rows = 1/1
+-----------------------------+
| someText                    |
|-----------------------------|
| \1\\2\\\3\\\\4\\\\\5\\\\\\6 |
+-----------------------------+
opensearchsql> select * from dbg where someText = "\1\\2\\\3\\\\4\\\\\5\\\\\\6";
fetched rows / total rows = 1/1
+-----------------------------+
| someText                    |
|-----------------------------|
| \1\\2\\\3\\\\4\\\\\5\\\\\\6 |
+-----------------------------+
opensearchsql> select * from dbg where someText = "\\1\\\\2\\\\\\3\\\\\\\\4\\\\\\\\\\5\\\\\\\\\\\\6";
fetched rows / total rows = 0/0
+------------+
| someText   |
|------------|
+------------+

3. Checkout this PR, build and install

4. Run the query again (with this fix):

opensearchsql> select * from dbg;
fetched rows / total rows = 1/1
+-----------------------------+
| someText                    |
|-----------------------------|
| \1\\2\\\3\\\\4\\\\\5\\\\\\6 |
+-----------------------------+
opensearchsql> select * from dbg where someText = "\1\\2\\\3\\\\4\\\\\5\\\\\\6";
fetched rows / total rows = 0/0
+------------+
| someText   |
|------------|
+------------+
opensearchsql> select * from dbg where someText = "\\1\\\\2\\\\\\3\\\\\\\\4\\\\\\\\\\5\\\\\\\\\\\\6";
fetched rows / total rows = 1/1
+-----------------------------+
| someText                    |
|-----------------------------|
| \1\\2\\\3\\\\4\\\\\5\\\\\\6 |
+-----------------------------+

5. Delete the index:

curl -XDELETE 'http://localhost:9200/dbg'

This PR affects how string literals processed only. Values are still returned as is, without processing escape sequences.