Improve parsing in interact mode of interfaces

[mwageringel]

The function Interface.interact() gives interactive access to the interpreter session of a pexpect interface that is running in the background. This ticket fixes the following issues with the output:

• whitespace is incorrectly stripped from the front of the output string
• special characters are not properly escaped
• the syntax sage(...) for evaluating expressions in Sage does not support nested parentheses

---

The whitespace issues are particularly frequent with interfaces that use ASCII art for printing like Mathematica and Macaulay2:

sage: macaulay2.interact()

  --> Switching to Macaulay2 <--

macaulay2: M = ZZ^2
2
ZZ

ZZ-module, free

An artificial example using a standard interface which shows whitespace and escaping issue:

sage: gap.interact()

  --> Switching to Gap <--

gap: Print("  \\\\")
\

With the usual gap.eval() the escaping is done correctly, but in the case of Gap, whitespace is still stripped from the front.

sage: gap.eval(r'Print("  \\\\")')
\\

I changed the Gap interface to preserve whitespace at the front in order to be able to add a doctest for interact using a standard interface.

As for the nested parentheses, the following example now works. The expressions sage(...) are evaluated in Sage and the results are converted to Gap. Previously, this only worked for very simple expressions not containing any parenthesis.

sage: %gap

  --> Switching to Gap <--

gap: 2 + sage((1+2)*gap(-(5-3)^2).sage()) - sage(1+(2-1))
-12

Component: interfaces

Keywords: macaulay2, gap

Author: Markus Wageringel

Branch/Commit: dc0d969

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/28439

[mwageringel]

Commit: 51dadd7

[mwageringel]

New commits:

2e3ffa3	28439: fix whitespace in interact mode of interfaces
51dadd7	28439: fix pyflakes issues

[mwageringel]

Author: Markus Wageringel

[mwageringel]

Branch: u/gh-mwageringel/28439

[mwageringel]

comment:2

I suggest testing this in the terminal, as in the Jupyter notebook there does not seem to be a way to exit the subshells.

The remaining pyflakes warning is a false positive.

[7ed8c4ca-6d56-4ae9-953a-41e42b4ed313]

Changed commit from 51dadd7 to 760de84

[7ed8c4ca-6d56-4ae9-953a-41e42b4ed313]

Branch pushed to git repo; I updated commit sha1. New commits:

760de84

28439: handle parsing of nested parentheses

[mwageringel]

comment:5

I have fixed another problem, see the description.

[mwageringel]

Description changed:

--- 
+++ 
@@ -2,6 +2,7 @@

 - whitespace is incorrectly stripped from the front of the output string
 - special characters are not properly escaped
+- the syntax `sage(...)` for evaluating expressions in Sage does not support nested parentheses

 The whitespace issues are particular frequent with interfaces that use ASCII art for printing like Mathematica and Macaulay2:

@@ -36,3 +37,14 @@

I changed the Gap interface to preserve whitespace at the front in order to be able to add a doctest for interact using a standard interface. + +As for the nested parentheses, the following example now works. The expressions sage(...) are evaluated in Sage and converted to Gap. + +``` +sage: %gap +

• --> Switching to Gap <--

• +gap: 2 + sage((1+2)*gap(-(5-3)^2).sage()) - sage(1+(2-1)) +-12 +```

[7ed8c4ca-6d56-4ae9-953a-41e42b4ed313]

Changed commit from 760de84 to dc0d969

[7ed8c4ca-6d56-4ae9-953a-41e42b4ed313]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

5547fe7	28439: fix whitespace in interact mode of interfaces
8e39d6d	28439: fix pyflakes issues
dc0d969	28439: handle parsing of nested parentheses

[mwageringel]

comment:7

Rebased to fix an incorrect trac link in the first commit spotted by the patchbot.

[mwageringel]

Description changed:

--- 
+++ 
@@ -4,7 +4,9 @@
 - special characters are not properly escaped
 - the syntax `sage(...)` for evaluating expressions in Sage does not support nested parentheses

-The whitespace issues are particular frequent with interfaces that use ASCII art for printing like Mathematica and Macaulay2:
+---
+
+The whitespace issues are particularly frequent with interfaces that use ASCII art for printing like Mathematica and Macaulay2:

sage: macaulay2.interact() @@ -38,7 +40,7 @@

I changed the Gap interface to preserve whitespace at the front in order to be able to add a doctest for interact using a standard interface.

-As for the nested parentheses, the following example now works. The expressions sage(...) are evaluated in Sage and converted to Gap. +As for the nested parentheses, the following example now works. The expressions sage(...) are evaluated in Sage and the results are converted to Gap. Previously, this only worked for very simple expressions not containing any parenthesis.

 sage: %gap

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:8

All of these changes make sense and look good.

[mwageringel]

comment:9

Thanks.

[slel]

comment:10

I kept noticing incorrect stripping of initial whitespace without ever doing anything about it.

Finally initial whitespace will be preserved. Wholehearted thanks for that!

[vbraun]

Changed branch from u/gh-mwageringel/28439 to dc0d969