Add core:text/regex

core/text/regex/common/common.odin

@@ -0,0 +1,27 @@
+// This package helps break dependency cycles.
+package regex_common
+
+// VM limitations
+MAX_CAPTURE_GROUPS :: 10
+MAX_PROGRAM_SIZE   :: int(max(i16))
+MAX_CLASSES        :: int(max(u8))
+
+Flag :: enum u8 {
+	// Global: try to match the pattern anywhere in the string.
+	Global,
+	// Multiline: treat `^` and `$` as if they also match newlines.
+	Multiline,
+	// Case Insensitive: treat `a-z` as if it was also `A-Z`.
+	Case_Insensitive,
+	// Ignore Whitespace: bypass unescaped whitespace outside of classes.
+	Ignore_Whitespace,
+	// Unicode: let the compiler and virtual machine know to expect Unicode strings.
+	Unicode,
+
+	// No Capture: avoid saving capture group data entirely.
+	No_Capture,
+	// No Optimization: do not pass the pattern through the optimizer; for debugging.
+	No_Optimization,
+}
+
+Flags :: bit_set[Flag; u8]

core/text/regex/common/debugging.odin

@@ -0,0 +1,25 @@
+package regex_common
+
+@require import "core:os"
+import "core:io"
+import "core:strings"
+
+ODIN_DEBUG_REGEX :: #config(ODIN_DEBUG_REGEX, false)
+
+when ODIN_DEBUG_REGEX {
+	debug_stream := os.stream_from_handle(os.stderr)
+}
+
+write_padded_hex :: proc(w: io.Writer, #any_int n, zeroes: int) {
+	sb := strings.builder_make()
+	defer strings.builder_destroy(&sb)
+
+	sbw := strings.to_writer(&sb)
+	io.write_int(sbw, n, 0x10)
+
+	io.write_string(w, "0x")
+	for _ in 0..<max(0, zeroes - strings.builder_len(sb)) {
+		io.write_byte(w, '0')
+	}
+	io.write_int(w, n, 0x10)
+}