Simple OpenQASM 3.0 expressions and casts #7593

comp-phys-marc · 2025-06-03T19:52:26Z

Context: We would like to support manipulating classical and quantum variables with simple expressions and casts in the OpenQASM 3.0 interpreter.

Description of the Change: Adds support for binary and unary expressions as well as casts.

Benefits: Allows more classical arithmetic to be done in QASM programs.

Possible Drawbacks: Does not support everything in the QASM 3.0 spec as of yet.

Related ShortCut Stories: [sc-92514]

Co-authored-by: Astral Cai <[email protected]>

…-be-executed' into feature/rebased-simple-gates-can-be-executed

- improve docstring - fix test name (spelling) - initialize wrapper variable

- Debug unrelated MBQC test failure in CI

astralcai · 2025-06-05T21:08:30Z

pennylane/io/qasm_interpreter.py

+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[0]:
+                    self.vars[name].val = value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[1]:
+                    self.vars[name].val = self.vars[name].val + 1
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[2]:
+                    self.vars[name].val += value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[3]:
+                    self.vars[name].val -= value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[4]:
+                    self.vars[name].val = self.vars[name].val * value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[5]:
+                    self.vars[name].val = self.vars[name].val / value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[6]:
+                    self.vars[name].val = self.vars[name].val & value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[7]:
+                    self.vars[name].val = self.vars[name].val | value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[8]:
+                    self.vars[name].val = self.vars[name].val ^ value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[9]:
+                    self.vars[name].val = self.vars[name].val << value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[10]:
+                    self.vars[name].val = self.vars[name].val >> value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[11]:
+                    self.vars[name].val = self.vars[name].val % value
+                if node.op.name == ASSIGNMENT_CLASSICAL_OPERATORS[12]:
+                    self.vars[name].val = self.vars[name].val ** value


LOL maybe a switch-case is better here?

haha sure if you prefer :')

I am scratching my head over this...

What's your Python version?

NVM yeah each case must be a literal, it cannot be dynamically indexed from a list. I think literals make the code a lot more readable here anyways.

Python should have called visit() instead of always interpreting a literal! haha

pennylane/io/qasm_interpreter.py

astralcai · 2025-06-06T16:29:47Z

pennylane/io/qasm_interpreter.py

+            if node.op.name in ASSIGNMENT_CLASSICAL_OPERATORS:
+                if node.op.name == "=":
+                    self.vars[name].val = value
+                if node.op.name == "++":
+                    self.vars[name].val = self.vars[name].val + 1
+                if node.op.name == "+=":
+                    self.vars[name].val += value
+                if node.op.name == "-=":
+                    self.vars[name].val -= value
+                if node.op.name == "*=":
+                    self.vars[name].val = self.vars[name].val * value
+                if node.op.name == "/=":
+                    self.vars[name].val = self.vars[name].val / value
+                if node.op.name == "&=":
+                    self.vars[name].val = self.vars[name].val & value
+                if node.op.name == "|=":
+                    self.vars[name].val = self.vars[name].val | value
+                if node.op.name == "^=":
+                    self.vars[name].val = self.vars[name].val ^ value
+                if node.op.name == "<<=":
+                    self.vars[name].val = self.vars[name].val << value
+                if node.op.name == ">>=":
+                    self.vars[name].val = self.vars[name].val >> value
+                if node.op.name == "%=":
+                    self.vars[name].val = self.vars[name].val % value
+                if node.op.name == "**=":
+                    self.vars[name].val = self.vars[name].val ** value


Suggested change

if node.op.name in ASSIGNMENT_CLASSICAL_OPERATORS:

if node.op.name == "=":

self.vars[name].val = value

if node.op.name == "++":

self.vars[name].val = self.vars[name].val + 1

if node.op.name == "+=":

self.vars[name].val += value

if node.op.name == "-=":

self.vars[name].val -= value

if node.op.name == "*=":

self.vars[name].val = self.vars[name].val * value

if node.op.name == "/=":

self.vars[name].val = self.vars[name].val / value

if node.op.name == "&=":

self.vars[name].val = self.vars[name].val & value

if node.op.name == "|=":

self.vars[name].val = self.vars[name].val | value

if node.op.name == "^=":

self.vars[name].val = self.vars[name].val ^ value

if node.op.name == "<<=":

self.vars[name].val = self.vars[name].val << value

if node.op.name == ">>=":

self.vars[name].val = self.vars[name].val >> value

if node.op.name == "%=":

self.vars[name].val = self.vars[name].val % value

if node.op.name == "**=":

self.vars[name].val = self.vars[name].val ** value

match node.op.name:

case "=":

self.vars[name].val = value

case "++":

self.vars[name].val = self.vars[name].val + 1

case "+=":

self.vars[name].val += value

case "-=":

self.vars[name].val -= value

case "*=":

self.vars[name].val = self.vars[name].val * value

case "/=":

self.vars[name].val = self.vars[name].val / value

case "&=":

self.vars[name].val = self.vars[name].val & value

case "|=":

self.vars[name].val = self.vars[name].val | value

case "^=":

self.vars[name].val = self.vars[name].val ^ value

case "<<=":

self.vars[name].val = self.vars[name].val << value

case ">>=":

self.vars[name].val = self.vars[name].val >> value

case "%=":

self.vars[name].val = self.vars[name].val % value

case "**=":

self.vars[name].val = self.vars[name].val ** value

case _:

raise SyntaxError(...)

This should work.

Should indeed!

pennylane/io/qasm_interpreter.py

astralcai · 2025-06-06T17:42:55Z

pennylane/io/qasm_interpreter.py

+        if node.op.name in NON_ASSIGNMENT_CLASSICAL_OPERATORS:
+            match node.op.name:
+                case "==":
+                    ret = lhs == rhs


Why not

Suggested change

ret = lhs == rhs

return lhs == rhs

That is a fine suggestion. No problem with that.

Co-authored-by: Astral Cai <[email protected]>

- use default switch case - return within cases - typo in comment

…e/expressions

codecov · 2025-06-06T20:35:48Z

Codecov Report

Attention: Patch coverage is 92.17391% with 9 lines in your changes missing coverage. Please review.

Project coverage is 99.66%. Comparing base (5322c9b) to head (28ccbf5).
Report is 3 commits behind head on master.

Files with missing lines	Patch %	Lines
pennylane/io/qasm_interpreter.py	92.17%	9 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7593      +/-   ##
==========================================
- Coverage   99.68%   99.66%   -0.02%     
==========================================
  Files         531      531              
  Lines       51979    52091     +112     
==========================================
+ Hits        51815    51919     +104     
- Misses        164      172       +8

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comp-phys-marc and others added 30 commits May 23, 2025 11:26

Run formatter

793080a

Debug test failure due to imports

cbc0c58

Run formatter

f2d25ea

Initialize context at the start

41c7687

Revert requirements-ci.txt

96ac13d

Use AnnotatedQueue() to verify execution order

50f106f

Format

c2a0c05

Merge branch 'master' into feature/rebased-simple-gates-can-be-executed

08db20c

Add retrieve_variable() method

a78d950

Add dev comment on supported modifier names

5ad362d

Add explicit raise for bad modifiers

6790579

Clearer NameError message for undeclared vars

8cbb4e8

pylint

492e1b2

pylint

314185d

Assert instead of raise on bad modifiers

267ac8f

Use an update rather than setting each val in context init

b3a7dc1

Co-authored-by: Astral Cai <[email protected]>

Remove spy from tests

545ff3a

Merge remote-tracking branch 'origin/feature/rebased-simple-gates-can…

4f44322

…-be-executed' into feature/rebased-simple-gates-can-be-executed

Merge branch 'master' into feature/rebased-simple-gates-can-be-executed

64fd014

Import ops

3bd7808

Repr qubits using names not ints

e280871

Run formatter

e459523

Use getattr to dispatch handlers

2ef8a2c

Run formatter

85ef639

PR feedback

bfac0fa

- improve docstring - fix test name (spelling) - initialize wrapper variable

Support end statements

c7d9a93

Trigger CI

e7baeeb

- Debug unrelated MBQC test failure in CI

Variables

61436fd

Variable declarations, assignments, retrievals

031eb57

[WIP] remove pre-compute

aa7236c

comp-phys-marc added 3 commits June 4, 2025 12:00

format

30d3180

Remove redundant logic in retrieve_variable

3afd579

Test unary exprs

22d1ba5

comp-phys-marc mentioned this pull request Jun 4, 2025

Variables can be declared, assigned, retrieved #7488

Merged

comp-phys-marc added 2 commits June 4, 2025 13:48

Merge branch 'feature/variables' into feature/expressions

4d74068

Roughly equal

467820b

comp-phys-marc requested review from albi3ro and astralcai June 5, 2025 21:03

astralcai reviewed Jun 5, 2025

View reviewed changes

Switch case

59a1248

Base automatically changed from feature/variables to master June 5, 2025 21:50

astralcai reviewed Jun 6, 2025

View reviewed changes

pennylane/io/qasm_interpreter.py Outdated Show resolved Hide resolved

comp-phys-marc added 4 commits June 6, 2025 09:00

Merge branch 'master' into feature/expressions

a7353d7

Merge branch 'master', fix switch

0e16fdc

Clean up merge

4a02d0b

Cleanup tests

98a3042

comp-phys-marc marked this pull request as ready for review June 6, 2025 15:36

comp-phys-marc changed the title ~~[WIP] Simple OpenQASM 3.0 expressions and casts~~ Simple OpenQASM 3.0 expressions and casts Jun 6, 2025

PennyLaneAI deleted a comment from github-actions bot Jun 6, 2025

astralcai reviewed Jun 6, 2025

View reviewed changes

comp-phys-marc and others added 8 commits June 6, 2025 13:43

pylint

fc33e3b

Typo in comment

f5bfd74

Co-authored-by: Astral Cai <[email protected]>

PR feedback

98458c4

- use default switch case - return within cases - typo in comment

Merge remote-tracking branch 'origin' into feature/expressions

ce3b163

Merge remote-tracking branch 'origin/feature/expressions' into featur…

10bf4d2

…e/expressions

Format

0fe1c7d

pylint

2849bd4

File paths for CI

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