Add support for DEFGATE ... AS PAULI-SUM

CHANGELOG.md

@@ -11,6 +11,7 @@ Changelog
 - LaTeX circuit output now ignores `RESET` instructions by default, rendering
   instead the (equivalent) program with `RESET` omitted. (@kilimanjaro,
   gh-1118).
+- `DEFGATE ... AS PAULI-SUM` is now supported (@ecpeterson, gh-1125).
 
 ### Bugfixes
 

pyquil/_parser/PyQuilListener.py

@@ -28,8 +28,9 @@
 
 from pyquil.gates import QUANTUM_GATES
 from pyquil.quilatom import (Addr, MemoryReference, Parameter, quil_cos, quil_cis, quil_exp,
-                             quil_sin, quil_sqrt)
-from pyquil.quilbase import (Gate, DefGate, DefPermutationGate, Measurement, JumpTarget, Label, Expression,
+                             quil_sin, quil_sqrt, FormalArgument)
+from pyquil.quilbase import (Gate, DefGate, DefPermutationGate, DefGateByPaulis,
+                             Measurement, JumpTarget, Label, Expression,
                              Nop, Halt, Jump, JumpWhen, JumpUnless, Reset, Wait,
                              ClassicalNot, ClassicalNeg, ClassicalAnd, ClassicalInclusiveOr,
                              ClassicalExclusiveOr,
@@ -118,6 +119,14 @@ def exitDefGate(self, ctx: QuilParser.DefGateContext):
             parameters = [_variable(v) for v in ctx.variable()]
             self.result.append(DefGate(gate_name, matrix, parameters))
 
+    def exitDefGateAsPauli(self, ctx: QuilParser.DefGateAsPauliContext):
+        from pyquil.paulis import PauliSum
+        gate_name = ctx.name().getText()
+        parameters = [_variable(c) for c in ctx.variable()]
+        arguments = [_formalQubit(q) for q in ctx.qubitVariable()]
+        body = PauliSum([_pauliTerm(t) for t in ctx.pauliTerms().pauliTerm()])
+        self.result.append(DefGateByPaulis(gate_name, parameters, arguments, body))
+
     # DEFCIRCUIT parsing:
     # When we enter a circuit definition we create a backup of the instructions seen up to that point. Then, when the
     # listener continues walking through the circuit instructions it will add to an empty list. Once we leave the
@@ -397,6 +406,19 @@ def exitMemoryDescriptor(self, ctx):
 """
 
 
+def _formalQubit(fq):
+    return FormalArgument(fq.getText())
+
+
+def _pauliTerm(term):
+    # type: (QuilParser.PauliTermContext) -> PauliTerm
+    from pyquil.paulis import PauliTerm
+    letters = term.IDENTIFIER().getText()
+    args = [_formalQubit(q) for q in term.qubitVariable()]
+    coeff = _expression(term.expression())
+    return PauliTerm.from_list(list(zip(letters, args)), coeff)
+
+
 def _qubit(qubit):
     # type: (QuilParser.QubitContext) -> Qubit
     return Qubit(int(qubit.getText()))

pyquil/_parser/Quil.g4

@@ -7,6 +7,7 @@ grammar Quil;
 quil                : allInstr? ( NEWLINE+ allInstr )* NEWLINE* EOF ;
 
 allInstr            : defGate
+                    | defGateAsPauli
                     | defCircuit
                     | instr
                     ;
@@ -47,6 +48,7 @@ modifier            : CONTROLLED
 // D. Gate Definitions
 
 defGate             : DEFGATE name (( LPAREN variable ( COMMA variable )* RPAREN ) | ( AS gatetype ))? COLON NEWLINE matrix ;
+defGateAsPauli      : DEFGATE name ( LPAREN ( variable ( COMMA variable )* )? RPAREN ) qubitVariable+ AS PAULISUM COLON NEWLINE pauliTerms ;
 
 variable            : PERCENTAGE IDENTIFIER ;
 gatetype            : MATRIX
@@ -55,6 +57,9 @@ gatetype            : MATRIX
 matrix              : ( matrixRow NEWLINE )* matrixRow ;
 matrixRow           : TAB expression ( COMMA expression )* ;
 
+pauliTerms          : ( pauliTerm NEWLINE )* pauliTerm;
+pauliTerm           : TAB IDENTIFIER LPAREN expression RPAREN qubitVariable+ ;
+
 // E. Circuits
 
 defCircuit          : DEFCIRCUIT name ( LPAREN variable ( COMMA variable )* RPAREN )? qubitVariable* COLON NEWLINE circuit ;
@@ -171,6 +176,7 @@ OFFSET              : 'OFFSET' ;
 AS                  : 'AS' ;
 MATRIX              : 'MATRIX' ;
 PERMUTATION         : 'PERMUTATION' ;
+PAULISUM            : 'PAULI-SUM';
 
 NEG                 : 'NEG' ;
 NOT                 : 'NOT' ;

pyquil/_parser/gen3/Quil.tokens

@@ -17,63 +17,64 @@ OFFSET=16
 AS=17
 MATRIX=18
 PERMUTATION=19
-NEG=20
-NOT=21
-TRUE=22
-FALSE=23
-AND=24
-IOR=25
-XOR=26
-OR=27
-ADD=28
-SUB=29
-MUL=30
-DIV=31
-MOVE=32
-EXCHANGE=33
-CONVERT=34
-EQ=35
-GT=36
-GE=37
-LT=38
-LE=39
-LOAD=40
-STORE=41
-PI=42
-I=43
-SIN=44
-COS=45
-SQRT=46
-EXP=47
-CIS=48
-PLUS=49
-MINUS=50
-TIMES=51
-DIVIDE=52
-POWER=53
-CONTROLLED=54
-DAGGER=55
-FORKED=56
-IDENTIFIER=57
-INT=58
-FLOAT=59
-STRING=60
-PERIOD=61
-COMMA=62
-LPAREN=63
-RPAREN=64
-LBRACKET=65
-RBRACKET=66
-COLON=67
-PERCENTAGE=68
-AT=69
-QUOTE=70
-UNDERSCORE=71
-TAB=72
-NEWLINE=73
-COMMENT=74
-SPACE=75
-INVALID=76
+PAULISUM=20
+NEG=21
+NOT=22
+TRUE=23
+FALSE=24
+AND=25
+IOR=26
+XOR=27
+OR=28
+ADD=29
+SUB=30
+MUL=31
+DIV=32
+MOVE=33
+EXCHANGE=34
+CONVERT=35
+EQ=36
+GT=37
+GE=38
+LT=39
+LE=40
+LOAD=41
+STORE=42
+PI=43
+I=44
+SIN=45
+COS=46
+SQRT=47
+EXP=48
+CIS=49
+PLUS=50
+MINUS=51
+TIMES=52
+DIVIDE=53
+POWER=54
+CONTROLLED=55
+DAGGER=56
+FORKED=57
+IDENTIFIER=58
+INT=59
+FLOAT=60
+STRING=61
+PERIOD=62
+COMMA=63
+LPAREN=64
+RPAREN=65
+LBRACKET=66
+RBRACKET=67
+COLON=68
+PERCENTAGE=69
+AT=70
+QUOTE=71
+UNDERSCORE=72
+TAB=73
+NEWLINE=74
+COMMENT=75
+SPACE=76
+INVALID=77
 'DEFGATE'=1
 'DEFCIRCUIT'=2
 'MEASURE'=3
@@ -93,53 +94,54 @@ INVALID=76
 'AS'=17
 'MATRIX'=18
 'PERMUTATION'=19
-'NEG'=20
-'NOT'=21
-'TRUE'=22
-'FALSE'=23
-'AND'=24
-'IOR'=25
-'XOR'=26
-'OR'=27
-'ADD'=28
-'SUB'=29
-'MUL'=30
-'DIV'=31
-'MOVE'=32
-'EXCHANGE'=33
-'CONVERT'=34
-'EQ'=35
-'GT'=36
-'GE'=37
-'LT'=38
-'LE'=39
-'LOAD'=40
-'STORE'=41
-'pi'=42
-'i'=43
-'SIN'=44
-'COS'=45
-'SQRT'=46
-'EXP'=47
-'CIS'=48
-'+'=49
-'-'=50
-'*'=51
-'/'=52
-'^'=53
-'CONTROLLED'=54
-'DAGGER'=55
-'FORKED'=56
-'.'=61
-','=62
-'('=63
-')'=64
-'['=65
-']'=66
-':'=67
-'%'=68
-'@'=69
-'"'=70
-'_'=71
-'    '=72
-' '=75
+'PAULI-SUM'=20
+'NEG'=21
+'NOT'=22
+'TRUE'=23
+'FALSE'=24
+'AND'=25
+'IOR'=26
+'XOR'=27
+'OR'=28
+'ADD'=29
+'SUB'=30
+'MUL'=31
+'DIV'=32
+'MOVE'=33
+'EXCHANGE'=34
+'CONVERT'=35
+'EQ'=36
+'GT'=37
+'GE'=38
+'LT'=39
+'LE'=40
+'LOAD'=41
+'STORE'=42
+'pi'=43
+'i'=44
+'SIN'=45
+'COS'=46
+'SQRT'=47
+'EXP'=48
+'CIS'=49
+'+'=50
+'-'=51
+'*'=52
+'/'=53
+'^'=54
+'CONTROLLED'=55
+'DAGGER'=56
+'FORKED'=57
+'.'=62
+','=63
+'('=64
+')'=65
+'['=66
+']'=67
+':'=68
+'%'=69
+'@'=70
+'"'=71
+'_'=72
+'    '=73
+' '=76