From 77e9fefdbd70ad9bb351bf4b230d84c181d93156 Mon Sep 17 00:00:00 2001
From: Charlie Stanton <charlie@shtanton.xyz>
Date: Sun, 26 Feb 2023 10:04:53 +0000
Subject: Adds syntax to recognise and deal with starting and ending arrays,
 maps and strings

---
 subex/parse.go | 123 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)

diff --git a/subex/parse.go b/subex/parse.go
index 0c79dc3..db07567 100644
--- a/subex/parse.go
+++ b/subex/parse.go
@@ -5,6 +5,8 @@ import (
 )
 
 func parseReplacement(l *RuneReader) (output []TransducerOutput) {
+	// TODO escaping
+	// TODO refactor all the terminator stuff @, #, ~
 	loop: for {
 		r := l.next()
 		switch r {
@@ -18,6 +20,33 @@ func parseReplacement(l *RuneReader) (output []TransducerOutput) {
 					panic("Missing slot character")
 				}
 				output = append(output, TransducerReplacementLoad{datum: slot})
+			case '@':
+				terminal := l.next()
+				if terminal == '(' {
+					output = append(output, TransducerReplacementRune{datum: walk.ArrayBegin})
+				} else if terminal == ')' {
+					output = append(output, TransducerReplacementRune{datum: walk.ArrayEnd})
+				} else {
+					panic("Expected ( or ) after @")
+				}
+			case '~':
+				terminal := l.next()
+				if terminal == '(' {
+					output = append(output, TransducerReplacementRune{datum: walk.StartString{}})
+				} else if terminal == ')' {
+					output = append(output, TransducerReplacementRune{datum: walk.EndString{}})
+				} else {
+					panic("Expected ( or ) after ~")
+				}
+			case '#':
+				terminal := l.next()
+				if terminal == '(' {
+					output = append(output, TransducerReplacementRune{datum: walk.MapBegin})
+				} else if terminal == ')' {
+					output = append(output, TransducerReplacementRune{datum: walk.MapEnd})
+				} else {
+					panic("Expected ( or ) after #")
+				}
 			default:
 				output = append(output, TransducerReplacementRune{datum: r})
 		}
@@ -27,6 +56,7 @@ func parseReplacement(l *RuneReader) (output []TransducerOutput) {
 
 // Parse the contents of a range subex [] into a map
 func parseRangeSubex(l *RuneReader) map[walk.Datum]walk.Datum {
+	// TODO escaping
 	parts := make(map[walk.Datum]walk.Datum)
 	var froms []walk.Datum
 	var hasTo bool
@@ -38,6 +68,39 @@ func parseRangeSubex(l *RuneReader) map[walk.Datum]walk.Datum {
 		} else if fromsStart == '=' {
 			hasTo = true
 			break
+		} else if fromsStart == '@' {
+			terminal := l.next()
+			if terminal == '(' {
+				froms = append(froms, walk.ArrayBegin)
+				continue
+			} else if terminal == ')' {
+				froms = append(froms, walk.ArrayEnd)
+				continue
+			} else {
+				panic("Expected ( or ) after @")
+			}
+		} else if fromsStart == '#' {
+			terminal := l.next()
+			if terminal == '(' {
+				froms = append(froms, walk.MapBegin)
+				continue
+			} else if terminal == ')' {
+				froms = append(froms, walk.MapEnd)
+				continue
+			} else {
+				panic("Expected ( or ) after #")
+			}
+		} else if fromsStart == '~' {
+			terminal := l.next()
+			if terminal == '(' {
+				froms = append(froms, walk.StartString{})
+				continue
+			} else if terminal == ')' {
+				froms = append(froms, walk.EndString{})
+				continue
+			} else {
+				panic("Expected ( or ) after ~")
+			}
 		}
 		if l.accept("-") {
 			fromsEnd := l.next()
@@ -62,6 +125,39 @@ func parseRangeSubex(l *RuneReader) map[walk.Datum]walk.Datum {
 			tosStart := l.next()
 			if tosStart == ']' {
 				break
+			} else if tosStart == '@' {
+				terminal := l.next()
+				if terminal == '(' {
+					tos = append(tos, walk.ArrayBegin)
+					continue
+				} else if terminal == ')' {
+					tos = append(tos, walk.ArrayEnd)
+					continue
+				} else {
+					panic("Expected ( or ) after @")
+				}
+			} else if tosStart == '#' {
+				terminal := l.next()
+				if terminal == '(' {
+					tos = append(tos, walk.MapBegin)
+					continue
+				} else if terminal == ')' {
+					tos = append(tos, walk.MapEnd)
+					continue
+				} else {
+					panic("Expected ( or ) after #")
+				}
+			} else if tosStart == '~' {
+				terminal := l.next()
+				if terminal == '(' {
+					tos = append(tos, walk.StartString{})
+					continue
+				} else if terminal == ')' {
+					tos = append(tos, walk.EndString{})
+					continue
+				} else {
+					panic("Expected ( or ) after ~")
+				}
 			}
 			if l.accept("-") {
 				tosEnd := l.next()
@@ -124,6 +220,33 @@ func parseSubex(l *RuneReader, minPower int) SubexAST {
 			lhs = SubexASTOutput{replacement}
 		case '.':
 			lhs = SubexASTCopyAny{}
+		case '@':
+			terminal := l.next()
+			if terminal == '(' {
+				lhs = SubexASTCopyRune{datum: walk.ArrayBegin}
+			} else if terminal == ')' {
+				lhs = SubexASTCopyRune{datum: walk.ArrayEnd}
+			} else {
+				panic("Expected ( or ) after @")
+			}
+		case '~':
+			terminal := l.next()
+			if terminal == '(' {
+				lhs = SubexASTCopyRune{datum: walk.StartString{}}
+			} else if terminal == ')' {
+				lhs = SubexASTCopyRune{datum: walk.EndString{}}
+			} else {
+				panic("Expected ( or ) after ~")
+			}
+		case '#':
+			terminal := l.next()
+			if terminal == '(' {
+				lhs = SubexASTCopyRune{datum: walk.MapBegin}
+			} else if terminal == ')' {
+				lhs = SubexASTCopyRune{datum: walk.MapEnd}
+			} else {
+				panic("Expected ( or ) after #")
+			}
 		default:
 			lhs = SubexASTCopyRune{datum: r}
 	}
-- 
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