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/parse.go      | 13 ++++-------
 subex/subexast.go   | 12 +++++++++++
 subex/subexstate.go | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+), 9 deletions(-)

diff --git a/subex/parse.go b/subex/parse.go
index 6e1493b..0208142 100644
--- a/subex/parse.go
+++ b/subex/parse.go
@@ -206,7 +206,7 @@ func parseSubex(l *RuneReader, minPower int) SubexAST {
 		case '[':
 			rangeParts := parseRangeSubex(l)
 			lhs = SubexASTRange {rangeParts}
-		case ')', '|', ';', '{':
+		case ')', '|', ';', '{', '+':
 			l.rewind()
 			return nil
 		case '$':
@@ -243,10 +243,12 @@ func parseSubex(l *RuneReader, minPower int) SubexAST {
 		r := l.next()
 		switch {
 			case r == '{' && minPower <= 8:
-				lhs = SubexASTRepeat{
+				lhs = SubexASTRepeat {
 					content: lhs,
 					acceptable: parseRepeatRange(l),
 				}
+			case r == '+' && minPower <= 8:
+				lhs = SubexASTSum {lhs}
 			case r == '|' && minPower <= 4:
 				rhs := parseSubex(l, 5)
 				if rhs == nil {
@@ -262,13 +264,6 @@ func parseSubex(l *RuneReader, minPower int) SubexAST {
 					content: lhs,
 					delimiter: rhs,
 				}
-			//case r == '+' && minPower <= 6:
-			//	rhs := parseSubex(l, 7)
-			//	if rhs == nil {
-			//		panic("Missing subex after +")
-			//	}
-			//	// TODO: Implement this. Runs subex on the left, then subex on the right, then sums the outputs of each and outputs that
-			//	lhs = SubexASTAdd{lhs, rhs}
 			default:
 				l.rewind()
 				break loop
diff --git a/subex/subexast.go b/subex/subexast.go
index 5e63f03..9e7067b 100644
--- a/subex/subexast.go
+++ b/subex/subexast.go
@@ -181,3 +181,15 @@ func (ast SubexASTRange) compileWith(next SubexState) SubexState {
 		next: next,
 	}
 }
+
+// Run content and then assume that output is a series of numbers, sum them and output the total
+// Will cast strings, booleans and null to numbers
+type SubexASTSum struct {
+	content SubexAST
+}
+func (ast SubexASTSum) compileWith(next SubexState) SubexState {
+	return &SubexSumState {
+		inputState: ast.content.compileWith(&SubexNoneState{}),
+		next: next,
+	}
+}
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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