From ffd1b73b4f3294d9f3aa2ed600da3ba053aeb47c Mon Sep 17 00:00:00 2001
From: Charlie Stanton <charlie@shtanton.xyz>
Date: Tue, 18 Apr 2023 15:07:52 +0100
Subject: Adds the sum operator

Currently doesn't parse strings as each atom is considered independantly. Instead individual characters in strings can be cast
---
 subex/subexstate.go | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

(limited to 'subex/subexstate.go')

diff --git a/subex/subexstate.go b/subex/subexstate.go
index 3c554a2..cbcd210 100644
--- a/subex/subexstate.go
+++ b/subex/subexstate.go
@@ -188,3 +188,65 @@ func (state SubexRangeState) eat(store Store, char walk.Atom) []SubexBranch {
 func (state SubexRangeState) accepting(store Store) [][]walk.Atom {
 	return nil
 }
+
+func sumValues(values []walk.Atom) walk.ValueNumber {
+	var sum float64 = 0
+	for _, value := range values {
+		switch v := value.(type) {
+			case walk.ValueBool:
+				if (bool(v)) {
+					sum += 1
+				}
+			case walk.ValueNumber:
+				sum += float64(v)
+			case rune:
+				if '0' <= v && v <= '9' {
+					sum += float64(v - '0')
+				}
+			default:
+		}
+	}
+	return walk.ValueNumber(sum)
+}
+
+// Run the inputState machine and sum any values output, output the sum
+// Cast non numbers into numbers, ignore anything uncastable
+type SubexSumState struct {
+	inputState SubexState
+	next SubexState
+	sum walk.ValueNumber
+}
+func (state SubexSumState) eat(store Store, char walk.Atom) (nextStates []SubexBranch) {
+	acceptedOutputs := state.inputState.accepting(store)
+	for _, acceptedOutput := range acceptedOutputs {
+		nextNextStates := state.next.eat(store.clone(), char)
+		for i := range nextNextStates {
+			nextNextStates[i].output = walk.ConcatData([]walk.Atom{sumValues(append(acceptedOutput, state.sum))}, nextNextStates[i].output)
+		}
+		nextStates = append(nextStates, nextNextStates...)
+	}
+	nextInputStates := state.inputState.eat(store.clone(), char)
+	for _, inputState := range nextInputStates {
+		nextStates = append(nextStates, SubexBranch {
+			state: &SubexSumState {
+				inputState: inputState.state,
+				next: state.next,
+				sum: sumValues(append(inputState.output, state.sum)),
+			},
+			output: nil,
+			store: inputState.store,
+		})
+	}
+	return nextStates
+}
+func (state SubexSumState) accepting(store Store) (outputs [][]walk.Atom) {
+	acceptedOutputs := state.inputState.accepting(store)
+	for _, acceptedOutput := range acceptedOutputs {
+		nextOutputs := state.next.accepting(store.clone())
+		for i := range nextOutputs {
+			nextOutputs[i] = walk.ConcatData([]walk.Atom{sumValues(append(acceptedOutput, state.sum))}, nextOutputs[i])
+		}
+		outputs = append(outputs, nextOutputs...)
+	}
+	return outputs
+}
-- 
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