feature: Add parsing support for barrier/reset/delay/duration (#52)

* change: Add parsing for delay

* change: Add Reset, Barrier, Delay instructions and tests

* change: Test for Barrier

* change: Tests for other no-ops and reorg

* change: More tests for no-ops

* fix: Support for mu-s, dt

* fix: Include new docstrings

Author: kshyatt-aws

docs/src/circuits.md

@@ -12,6 +12,9 @@ BraketSimulator.Circuit
 BraketSimulator.Operator
 BraketSimulator.QuantumOperator
 BraketSimulator.FreeParameter
+BraketSimulator.Reset
+BraketSimulator.Barrier
+BraketSimulator.Delay
 BraketSimulator.Measure
 BraketSimulator.Instruction
 BraketSimulator.QubitSet

src/Quasar.jl

@@ -1,7 +1,7 @@
 module Quasar
 
 using ..BraketSimulator
-using Automa, AbstractTrees, DataStructures
+using Automa, AbstractTrees, DataStructures, Dates
 using DataStructures: Stack
 using BraketSimulator: Control, Instruction, Result, bind_value!, remap, qubit_count, Circuit
 
@@ -71,9 +71,7 @@ const qasm_tokens = [
         :arrow_token  => re"->",
         :reset_token  => re"reset",
         :delay_token  => re"delay",
-        :stretch_token  => re"stretch",
-        :barrier_token  => re"barrier",
-        :duration_token  => re"duration",
+        :barrier_token => re"barrier",
         :void         => re"void",
         :const_token  => re"const",
         :assignment   => re"=|-=|\+=|\*=|/=|^=|&=|\|=|<<=|>>=",
@@ -110,12 +108,18 @@ const qasm_tokens = [
         :string_token    => '"' * rep(re"[ !#-~]" | re"\\\\\"") * '"' | '\'' * rep(re"[ -&(-~]" | ('\\' * re"[ -~]")) * '\'',
         :newline         => re"\r?\n",
         :spaces          => re"[\t ]+",
-        :durationof_token  => re"durationof", # this MUST be lower than duration_token to preempt duration
-        :classical_type    => re"bool|uint|int|float|angle|complex|array|bit",
-        :duration_value    => (float | integer) * re"ns|µs|us|ms|s",
+        :classical_type    => re"bool|uint|int|float|angle|complex|array|bit|stretch|duration",
+        :durationof_token  => re"durationof", # this MUST be lower than classical_type to preempt duration
+        :duration_literal  => (float | integer) * re"dt|ns|us|ms|s|\xce\xbc\x73", # transcode'd μs
         :forbidden_keyword => re"cal|defcal|extern",
 ]
 
+const dt_type = Ref{DataType}()
+
+function __init__()
+    dt_type[] = Nanosecond
+end
+
 @eval @enum Token error $(first.(qasm_tokens)...)
 make_tokenizer((error,
     [Token(i) => j for (i,j) in enumerate(last.(qasm_tokens))]
@@ -369,6 +373,15 @@ function parse_classical_type(tokens, stack, start, qasm)
         first(array_tokens)[end] == comma && popfirst!(array_tokens)
         size   = parse_expression(array_tokens, stack, start, qasm)
         return QasmExpression(:classical_type, SizedArray(eltype, size))
+    elseif var_type == "duration"
+        @warn "duration expression encountered -- currently `duration` is a no-op"
+        # TODO: add proper parsing of duration expressions, including
+        # support for units and algebraic durations like 2*a.
+        return QasmExpression(:classical_type, :duration)
+    elseif var_type == "stretch"
+        @warn "stretch expression encountered -- currently `stretch` is a no-op"
+        # TODO: add proper parsing of stretch expressions
+        return QasmExpression(:classical_type, :stretch)
     else
         !any(triplet->triplet[end] == semicolon, tokens) && push!(tokens, (-1, Int32(-1), semicolon))
         size = is_sized ? parse_expression(tokens, stack, start, qasm) : QasmExpression(:integer_literal, -1)
@@ -427,6 +440,21 @@ parse_oct_literal(token, qasm)     = QasmExpression(:integer_literal, tryparse(I
 parse_bin_literal(token, qasm)     = QasmExpression(:integer_literal, tryparse(Int, qasm[token[1]:token[1]+token[2]-1]))
 parse_float_literal(token, qasm)   = QasmExpression(:float_literal, tryparse(Float64, qasm[token[1]:token[1]+token[2]-1]))
 parse_boolean_literal(token, qasm)   = QasmExpression(:boolean_literal, tryparse(Bool, qasm[token[1]:token[1]+token[2]-1]))
+function parse_duration_literal(token, qasm)
+    str = String(codeunits(qasm)[token[1]:token[1]+token[2]-1])
+    duration = if endswith(str, "ns")
+            Nanosecond(tryparse(Int, chop(str, tail=2)))
+        elseif endswith(str, "ms")
+            Millisecond(tryparse(Int, chop(str, tail=2)))
+        elseif endswith(str, "us") || endswith(str, "μs")
+            Microsecond(tryparse(Int, chop(str, tail=2)))
+        elseif endswith(str, "s")
+            Second(tryparse(Int, chop(str, tail=1)))
+        elseif endswith(str, "dt")
+            dt_type[](tryparse(Int, chop(str, tail=2)))
+        end
+    QasmExpression(:duration_literal, duration)
+end
 function parse_irrational_literal(token, qasm)
     raw_string = String(codeunits(qasm)[token[1]:token[1]+token[2]-1])
     raw_string == "pi" && return QasmExpression(:irrational_literal, π)
@@ -463,7 +491,7 @@ function extract_braced_block(tokens::Vector{Tuple{Int64, Int32, Token}}, stack,
         next_token[end] == rbracket && (closers_met += 1)
         push!(braced_tokens, next_token)
     end
-    pop!(braced_tokens) # closing }
+    pop!(braced_tokens) # closing ]
     push!(braced_tokens, (-1, Int32(-1), semicolon))
     return braced_tokens
 end
@@ -511,6 +539,7 @@ function parse_list_expression(tokens::Vector{Tuple{Int64, Int32, Token}}, stack
 end
 
 function parse_literal(tokens::Vector{Tuple{Int64, Int32, Token}}, stack, start, qasm)
+    tokens[1][end] == duration_literal && return parse_duration_literal(popfirst!(tokens), qasm) 
     tokens[1][end] == string_token && return parse_string_literal(popfirst!(tokens), qasm) 
     tokens[1][end] == hex     && return parse_hex_literal(popfirst!(tokens), qasm) 
     tokens[1][end] == oct     && return parse_oct_literal(popfirst!(tokens), qasm) 
@@ -634,7 +663,7 @@ function parse_expression(tokens::Vector{Tuple{Int64, Int32, Token}}, stack, sta
         token_name = parse_bracketed_expression(pushfirst!(tokens, start_token), stack, start, qasm) 
     elseif start_token[end] == classical_type 
         token_name = parse_classical_type(pushfirst!(tokens, start_token), stack, start, qasm)
-    elseif start_token[end] ∈ (string_token, integer_token, float_token, hex, oct, bin, irrational, dot, boolean)
+    elseif start_token[end] ∈ (string_token, integer_token, float_token, hex, oct, bin, irrational, dot, boolean, duration_literal)
         token_name = parse_literal(pushfirst!(tokens, start_token), stack, start, qasm)
     elseif start_token[end] ∈ (mutable, readonly, const_token)
         token_name = parse_identifier(start_token, qasm)
@@ -644,7 +673,6 @@ function parse_expression(tokens::Vector{Tuple{Int64, Int32, Token}}, stack, sta
         token_name = QasmExpression(:n_dims, QasmExpression(:integer_literal, parse(Int, dim)))
     end
     head(token_name) == :empty && throw(QasmParseError("unable to parse line with start token $(start_token[end])", stack, start, qasm))
-
     next_token = first(tokens)
     if next_token[end] == semicolon || next_token[end] == comma || start_token[end] ∈ (lbracket, lbrace)
         expr = token_name
@@ -657,7 +685,7 @@ function parse_expression(tokens::Vector{Tuple{Int64, Int32, Token}}, stack, sta
         unary_op_symbol ∈ (:~, :!, :-) || throw(QasmParseError("invalid unary operator $unary_op_symbol.", stack, start, qasm))
         next_expr = parse_expression(tokens, stack, start, qasm)
         # apply unary op to next_expr
-        if head(next_expr) ∈ (:identifier, :indexed_identifier, :integer_literal, :float_literal, :string_literal, :irrational_literal, :boolean_literal, :complex_literal, :function_call, :cast)
+        if head(next_expr) ∈ (:identifier, :indexed_identifier, :integer_literal, :float_literal, :string_literal, :irrational_literal, :boolean_literal, :complex_literal, :function_call, :cast, :duration_literal)
             expr = QasmExpression(:unary_op, unary_op_symbol, next_expr)
         elseif head(next_expr) == :binary_op
             # replace first argument
@@ -1005,36 +1033,37 @@ function parse_qasm(clean_tokens::Vector{Tuple{Int64, Int32, Token}}, qasm::Stri
             line_exprs = collect(Iterators.reverse(line_body))[2:end]
             push!(stack, QasmExpression(:return, line_exprs))
         elseif token == box
-            @warn "box expression encountered -- currently boxed and delayed expressions are not supported"
+            @warn "box expression encountered -- currently `box` is a no-op"
             box_expr = QasmExpression(:box)
             parse_block_body(box_expr, clean_tokens, stack, start, qasm)
             push!(stack, box_expr)
         elseif token == reset_token
             @warn "reset expression encountered -- currently `reset` is a no-op"
             eol = findfirst(triplet->triplet[end] == semicolon, clean_tokens)
             reset_tokens = splice!(clean_tokens, 1:eol)
-            targets = parse_expression(reset_tokens, stack, start, qasm)
+            targets = parse_list_expression(reset_tokens, stack, start, qasm)
             push!(stack, QasmExpression(:reset, targets))
         elseif token == barrier_token
             @warn "barrier expression encountered -- currently `barrier` is a no-op"
             eol = findfirst(triplet->triplet[end] == semicolon, clean_tokens)
             barrier_tokens = splice!(clean_tokens, 1:eol)
-            targets = parse_expression(barrier_tokens, stack, start, qasm)
+            targets = parse_list_expression(barrier_tokens, stack, start, qasm)
             push!(stack, QasmExpression(:barrier, targets))
-        elseif token == duration_token
-            @warn "duration expression encountered -- currently `duration` is a no-op"
-            eol = findfirst(triplet->triplet[end] == semicolon, clean_tokens)
-            duration_tokens = splice!(clean_tokens, 1:eol)
-            # TODO: add proper parsing of duration expressions, including
-            # support for units and algebraic durations like 2*a.
-            #dur_expr = parse_expression(duration_tokens, stack, start, qasm)
-            push!(stack, QasmExpression(:duration))
-        elseif token == stretch_token
-            @warn "stretch expression encountered -- currently `stretch` is a no-op"
+        elseif token == delay_token
+            @warn "delay expression encountered -- currently `delay` is a no-op"
             eol = findfirst(triplet->triplet[end] == semicolon, clean_tokens)
-            stretch_tokens = splice!(clean_tokens, 1:eol)
-            stretch_expr = parse_expression(stretch_tokens, stack, start, qasm)
-            push!(stack, QasmExpression(:stretch, stretch_expr))
+            delay_tokens = splice!(clean_tokens, 1:eol)
+            delay_expr   = QasmExpression(:delay)
+            # format is delay[duration]; or delay[duration] targets;
+            delay_duration = extract_braced_block(delay_tokens, stack, start, qasm)
+            push!(delay_expr, QasmExpression(:duration, parse_expression(delay_duration, stack, start, qasm)))
+            target_expr = QasmExpression(:targets)
+            if first(delay_tokens)[end] != semicolon # targets present
+                targets = parse_list_expression(delay_tokens, stack, start, qasm)
+                push!(target_expr, targets)
+            end
+            push!(delay_expr, target_expr)
+            push!(stack, delay_expr)
         elseif token == end_token
             push!(stack, QasmExpression(:end))
         elseif token == identifier || token == builtin_gate
@@ -1327,7 +1356,7 @@ function evaluate(v::V, expr::QasmExpression) where {V<:AbstractVisitor}
         step::Int  = evaluate(v, raw_step)
         stop::Int  = evaluate(v, raw_stop)
         return StepRange(start, step, stop)
-    elseif head(expr) ∈ (:integer_literal, :float_literal, :string_literal, :complex_literal, :irrational_literal, :boolean_literal)
+    elseif head(expr) ∈ (:integer_literal, :float_literal, :string_literal, :complex_literal, :irrational_literal, :boolean_literal, :duration_literal)
         return expr.args[1]
     elseif head(expr) == :array_literal
         return [evaluate(v, arg) for arg in convert(Vector{QasmExpression}, expr.args)]
@@ -1630,8 +1659,21 @@ function (v::AbstractVisitor)(program_expr::QasmExpression)
     elseif head(program_expr) == :version
         return v
     elseif head(program_expr) == :reset
+        targets = program_expr.args[1]::QasmExpression
+        target_qubits = evaluate(v, targets)
+        push!(v, [BraketSimulator.Instruction(BraketSimulator.Reset(), t) for t in target_qubits])
         return v
     elseif head(program_expr) == :barrier
+        targets = program_expr.args[1]::QasmExpression
+        target_qubits = evaluate(v, targets)
+        push!(v, [BraketSimulator.Instruction(BraketSimulator.Barrier(), t) for t in target_qubits])
+        return v
+    elseif head(program_expr) == :delay
+        duration_expr = program_expr.args[1].args[1]::QasmExpression
+        targets       = program_expr.args[2].args[1]::QasmExpression
+        target_qubits = evaluate(v, targets)
+        duration      = evaluate(v, duration_expr) 
+        push!(v, [BraketSimulator.Instruction(BraketSimulator.Delay(duration), t) for t in target_qubits])
         return v
     elseif head(program_expr) == :stretch
         return v

src/dm_simulator.jl

@@ -148,11 +148,15 @@ function _evolve_op!(
 ) where {T<:Complex,S<:AbstractDensityMatrix{T},N<:Noise}
     apply_noise!(op, dms.density_matrix, target...)
 end
-# Measure operators are no-ops for now as measurement is handled at the end
-# of simulation, in the results computation step. If/when mid-circuit
-# measurement is supported, this operation will collapse the density
-# matrix on the measured qubits.
+# Measure, barrier, reset, and delay operators are no-ops for now as
+# measurement is handled at the end of simulation, in the results
+# computation step. If/when mid-circuit # measurement is supported,
+# this operation will collapse the density # matrix on the measured qubits.
+# Barrier, reset, and delay are also to-do implementations.
 _evolve_op!(dms::DensityMatrixSimulator{T,S}, m::Measure, args...) where {T<:Complex,S<:AbstractDensityMatrix{T}} = return
+_evolve_op!(dms::DensityMatrixSimulator{T,S}, b::Barrier, args...) where {T<:Complex,S<:AbstractDensityMatrix{T}} = return
+_evolve_op!(dms::DensityMatrixSimulator{T,S}, r::Reset, args...) where {T<:Complex,S<:AbstractDensityMatrix{T}} = return
+_evolve_op!(dms::DensityMatrixSimulator{T,S}, d::Delay, args...) where {T<:Complex,S<:AbstractDensityMatrix{T}} = return
 
 """
     evolve!(dms::DensityMatrixSimulator{T, S<:AbstractMatrix{T}}, operations::Vector{Instruction}) -> DensityMatrixSimulator{T, S}

src/gate_kernels.jl

@@ -282,6 +282,9 @@ apply_gate!(::Val{false}, g::I, state_vec::AbstractStateVector{T}, qubits::Int..
 apply_gate!(::Val{true}, g::I, state_vec::AbstractStateVector{T}, qubits::Int...) where {T<:Complex} =
     return
 apply_gate!(::Measure, state_vec, args...) = return
+apply_gate!(::Reset, state_vec, args...) = return
+apply_gate!(::Barrier, state_vec, args...) = return
+apply_gate!(::Delay, state_vec, args...) = return
 
 function apply_gate!(
     g_matrix::Union{SMatrix{2,2,T}, Diagonal{T,SVector{2,T}}},

src/gates.jl

@@ -115,9 +115,6 @@ qubit_count(g::Unitary) = convert(Int, log2(size(g.matrix, 1)))
 Parametrizable(g::AngledGate) = Parametrized()
 Parametrizable(g::Gate)       = NonParametrized()
 parameters(g::AngledGate)     = collect(filter(a->a isa FreeParameter, angles(g)))
-parameters(g::Gate)           = FreeParameter[] 
-bind_value!(g::G, params::Dict{Symbol, <:Real}) where {G<:Gate} = bind_value!(Parametrizable(g), g, params)
-bind_value!(::NonParametrized, g::G, params::Dict{Symbol, <:Real}) where {G<:Gate} = g
 # nosemgrep
 function bind_value!(::Parametrized, g::G, params::Dict{Symbol, <:Real}) where {G<:AngledGate}
     new_angles = map(angles(g)) do angle

src/noises.jl

@@ -141,11 +141,9 @@ end
 Base.:(==)(c1::MultiQubitPauliChannel{N}, c2::MultiQubitPauliChannel{M}) where {N,M} = N == M && c1.probabilities == c2.probabilities
 
 Parametrizable(g::Noise) = NonParametrized()
-parameters(g::Noise) = parameters(Parametrizable(g), g)
+parameters(g::Noise)     = parameters(Parametrizable(g), g)
 parameters(::Parametrized, g::N) where {N<:Noise} = filter(x->x isa FreeParameter, [getproperty(g, fn) for fn in fieldnames(N)])
 parameters(::NonParametrized, g::Noise) = FreeParameter[]
-bind_value!(n::N, params::Dict{Symbol, <:Real}) where {N<:Noise} = bind_value!(Parametrizable(n), n, params)
-bind_value!(::NonParametrized, n::N, params::Dict{Symbol, <:Real}) where {N<:Noise} = n
 
 # nosemgrep
 function bind_value!(::Parametrized, g::N, params::Dict{Symbol, <:Real}) where {N<:Noise}

src/operators.jl

@@ -54,6 +54,8 @@ function Base.getindex(p::PauliEigenvalues{N}, i::Int)::Float64 where N
 end
 Base.getindex(p::PauliEigenvalues{N}, ix::Vector{Int}) where {N} = [p[i] for i in ix]
 
+parameters(o::QuantumOperator) = FreeParameter[] 
+
 """
     Measure(index) <: QuantumOperator
 
@@ -66,3 +68,47 @@ Measure() = Measure(-1)
 Parametrizable(m::Measure) = NonParametrized()
 qubit_count(::Type{Measure}) = 1
 qubit_count(m::Measure) = qubit_count(Measure)
+
+"""
+    Reset(index) <: QuantumOperator
+
+Represents an active reset operation on targeted qubit, stored in the classical register at `index`.
+For now, this is a no-op.
+"""
+struct Reset <: QuantumOperator
+    index::Int
+end
+Reset() = Reset(-1)
+Parametrizable(m::Reset) = NonParametrized()
+qubit_count(::Type{Reset}) = 1
+qubit_count(m::Reset) = qubit_count(Reset)
+
+"""
+    Barrier(index) <: QuantumOperator
+
+Represents a barrier operation on targeted qubit, stored in the classical register at `index`.
+For now, this is a no-op.
+"""
+struct Barrier <: QuantumOperator
+    index::Int
+end
+Barrier() = Barrier(-1)
+Parametrizable(m::Barrier) = NonParametrized()
+qubit_count(::Type{Barrier}) = 1
+qubit_count(m::Barrier) = qubit_count(Barrier)
+
+"""
+    Delay(index, duration::Time) <: QuantumOperator
+
+Represents a delay operation for `duration` on targeted qubit,
+stored in the classical register at `index`.
+For now, this is a no-op.
+"""
+struct Delay <: QuantumOperator
+    index::Int
+    duration::Dates.Period
+end
+Delay(duration::Dates.Period) = Delay(-1, duration)
+Parametrizable(m::Delay) = NonParametrized()
+qubit_count(::Type{Delay}) = 1
+qubit_count(m::Delay) = qubit_count(Delay)

src/schemas.jl

@@ -22,4 +22,6 @@ end
 Instruction(o::O, target) where {O<:Operator} = Instruction{O}(o, QubitSet(target...))
 Base.:(==)(ix1::Instruction{O}, ix2::Instruction{O}) where {O<:Operator} = (ix1.operator == ix2.operator && ix1.target == ix2.target)
 bind_value!(ix::Instruction{O}, param_values::Dict{Symbol, <:Real}) where {O<:Operator} = Instruction{O}(bind_value!(ix.operator, param_values), ix.target)
+bind_value!(o::O, params::Dict{Symbol, <:Real}) where {O<:Operator} = bind_value!(Parametrizable(o), o, params)
+bind_value!(::NonParametrized, o::O, params::Dict{Symbol, <:Real}) where {O<:Operator} = o
 remap(@nospecialize(ix::Instruction{O}), mapping::Dict{<:Integer, <:Integer}) where {O} = Instruction{O}(copy(ix.operator), [mapping[q] for q in ix.target])