7 files changed, 130 insertions, 14 deletions

diff --git a/bin/edi/Makefile b/bin/edi/Makefile
index 8ad154c6..2c98d9f2 100644
--- a/bin/edi/Makefile
+++ b/bin/edi/Makefile
@@ -4,10 +4,12 @@ LDLIBS = -lcursesw
 OBJS += buffer.o
 OBJS += edi.o
 OBJS += file.o
+OBJS += iter.o
 OBJS += log.o
 OBJS += table.o
 
 TESTS += buffer.t
+TESTS += iter.t
 TESTS += table.t
 
 all: tags edi test
diff --git a/bin/edi/buffer.c b/bin/edi/buffer.c
index 7297f411..5950317e 100644
--- a/bin/edi/buffer.c
+++ b/bin/edi/buffer.c
@@ -34,7 +34,6 @@ struct Buffer bufferAlloc(size_t cap) {
 	struct Block *block = blockAlloc(NULL, cap);
 	return (struct Buffer) {
 		.cap = cap,
-		.len = 0,
 		.slice = { block->chars, 0 },
 		.block = block,
 	};
diff --git a/bin/edi/edi.c b/bin/edi/edi.c
index c8cd2a44..fb6e3929 100644
--- a/bin/edi/edi.c
+++ b/bin/edi/edi.c
@@ -30,10 +30,8 @@ int main(int argc, char *argv[]) {
 	fileRead(&file);
 
 	const struct Table *table = &file.log.states[file.log.state].table;
-	for (size_t i = 0; i < table->len; ++i) {
-		for (size_t j = 0; j < table->slices[i].len; ++j) {
-			printf("%lc", table->slices[i].ptr[j]);
-		}
+	for (struct Iter it = iter(table, 0); it.ch != WEOF; it = iterNext(it)) {
+		printf("%lc", it.ch);
 	}
 
 	fileFree(&file);
diff --git a/bin/edi/edi.h b/bin/edi/edi.h
index 3425b235..6891b866 100644
--- a/bin/edi/edi.h
+++ b/bin/edi/edi.h
@@ -17,11 +17,15 @@
 #include <stdlib.h>
 #include <wchar.h>
 
-static inline struct Span {
+struct Span {
 	size_t at, to;
-} spanNext(struct Span span, size_t len) {
+};
+static inline struct Span spanNext(struct Span span, size_t len) {
 	return (struct Span) { span.to, span.to + len };
 }
+static inline struct Span spanPrev(struct Span span, size_t len) {
+	return (struct Span) { span.at - len, span.at };
+}
 
 struct Slice {
 	const wchar_t *ptr;
@@ -55,6 +59,17 @@ struct Table tableInsert(const struct Table *prev, size_t at, struct Slice ins);
 struct Table tableDelete(const struct Table *prev, struct Span del);
 void tableUpdate(struct Table *table, struct Slice ins);
 
+struct Iter {
+	const struct Table *table;
+	struct Span span;
+	size_t slice;
+	size_t at;
+	wint_t ch;
+};
+struct Iter iter(const struct Table *table, size_t at);
+struct Iter iterNext(struct Iter it);
+struct Iter iterPrev(struct Iter it);
+
 struct Log {
 	size_t cap, len;
 	size_t state;
diff --git a/bin/edi/file.c b/bin/edi/file.c
index 9f85d1da..55b7d679 100644
--- a/bin/edi/file.c
+++ b/bin/edi/file.c
@@ -34,7 +34,6 @@ struct File fileAlloc(char *path) {
 		.path = path,
 		.buf = bufferAlloc(BufCap),
 		.log = logAlloc(LogCap),
-		.clean = 0,
 	};
 	if (!path) logPush(&file.log, TableEmpty);
 	return file;
diff --git a/bin/edi/iter.c b/bin/edi/iter.c
new file mode 100644
index 00000000..cfbefc89
--- /dev/null
+++ b/bin/edi/iter.c
@@ -0,0 +1,108 @@
+/* Copyright (C) 2018  June McEnroe <june@causal.agency>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <wchar.h>
+
+#include "edi.h"
+
+struct Iter iter(const struct Table *table, size_t at) {
+	struct Span span = { 0, 0 };
+	size_t slice;
+	for (slice = 0; slice < table->len; ++slice) {
+		span = spanNext(span, table->slices[slice].len);
+		if (span.at <= at && span.to > at) break;
+	}
+	return (struct Iter) {
+		.table = table,
+		.span = span,
+		.slice = slice,
+		.at = (at < span.to ? at : span.to),
+		.ch = (at < span.to ? table->slices[slice].ptr[at - span.at] : WEOF),
+	};
+}
+
+struct Iter iterNext(struct Iter it) {
+	if (it.at == it.span.to && it.ch == WEOF) return it;
+	it.at++;
+	if (it.at == it.span.to) {
+		if (it.slice + 1 == it.table->len) {
+			it.ch = WEOF;
+			return it;
+		}
+		it.slice++;
+		it.span = spanNext(it.span, it.table->slices[it.slice].len);
+	}
+	it.ch = it.table->slices[it.slice].ptr[it.at - it.span.at];
+	return it;
+}
+
+struct Iter iterPrev(struct Iter it) {
+	if (it.at > it.span.to && it.ch == WEOF) return it;
+	it.at--;
+	if (it.at > it.span.to) {
+		it.ch = WEOF;
+		return it;
+	}
+	if (it.at < it.span.at) {
+		it.slice--;
+		it.span = spanPrev(it.span, it.table->slices[it.slice].len);
+	}
+	it.ch = it.table->slices[it.slice].ptr[it.at - it.span.at];
+	return it;
+}
+
+#ifdef TEST
+#include <assert.h>
+
+int main() {
+	struct Slice slices[2] = {
+		{ L"AB", 2 },
+		{ L"CD", 2 },
+	};
+	struct Table table = { .len = 2, .slices = slices };
+
+	assert(L'A' == iter(&table, 0).ch);
+	assert(L'B' == iter(&table, 1).ch);
+	assert(L'C' == iter(&table, 2).ch);
+	assert(L'D' == iter(&table, 3).ch);
+
+	assert(L'B' == iterNext(iter(&table, 0)).ch);
+	assert(L'C' == iterNext(iter(&table, 1)).ch);
+	assert(L'D' == iterNext(iter(&table, 2)).ch);
+	assert(WEOF == iterNext(iter(&table, 5)).ch);
+
+	assert(WEOF == iterPrev(iter(&table, 0)).ch);
+	assert(L'A' == iterPrev(iter(&table, 1)).ch);
+	assert(L'B' == iterPrev(iter(&table, 2)).ch);
+	assert(L'C' == iterPrev(iter(&table, 3)).ch);
+
+	struct Iter it = iter(&table, 3);
+	it = iterNext(it);
+	it = iterNext(it);
+	assert(WEOF == it.ch);
+	it = iterPrev(it);
+	assert(L'D' == it.ch);
+
+	it = iter(&table, 0);
+	it = iterPrev(it);
+	it = iterPrev(it);
+	assert(WEOF == it.ch);
+	it = iterNext(it);
+	assert(L'A' == it.ch);
+}
+
+#endif
diff --git a/bin/edi/table.c b/bin/edi/table.c
index 593766a4..7905d7d7 100644
--- a/bin/edi/table.c
+++ b/bin/edi/table.c
@@ -24,12 +24,7 @@
 struct Table tableAlloc(size_t cap) {
 	struct Slice *slices = malloc(sizeof(*slices) * cap);
 	if (!slices) err(EX_OSERR, "malloc");
-	return (struct Table) {
-		.cap = cap,
-		.len = 0,
-		.ins = 0,
-		.slices = slices,
-	};
+	return (struct Table) { .cap = cap, .slices = slices };
 }
 
 void tableFree(struct Table *table) {