From 14419f066973d26192bea9b97707bd872af772c7 Mon Sep 17 00:00:00 2001
From: Paul Duncan <pabs@pablotron.org>
Date: Thu, 2 Mar 2023 17:09:02 -0500
Subject: initial commit

---
 section-parse.go | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 section-parse.go

(limited to 'section-parse.go')

diff --git a/section-parse.go b/section-parse.go
new file mode 100644
index 0000000..83c2ed2
--- /dev/null
+++ b/section-parse.go
@@ -0,0 +1,85 @@
+//
+// section-parse.go: scan standard input and do the following:
+//
+// 1. look for a section that begins with "test-text "STUFF/foo" and ends
+//    with a blank line.
+// 2. print the "bar.DIGITS" suffix for each line in the section
+//
+// Build:
+//
+//   go build section-parse.go
+//
+// Alternatively, you can run this script directly like this:
+//
+//   go run ./section-parse.go < input.txt
+//
+// Example:
+//
+//   > go run ./section-parse.go < input.txt
+//   bar.1
+//   bar.2
+//   bar.3
+//   bar.4
+//
+package main
+
+import (
+  "fmt"
+  "io"
+  "log"
+  "os"
+  "regexp"
+  "strings"
+)
+
+// section header regex
+var headerRe = regexp.MustCompile(`^test-text ".*/foo"$`)
+
+// section footer regex
+var footerRe = regexp.MustCompile(`^\s*$`)
+
+// body line regex
+var bodyRe = regexp.MustCompile(`^.*(bar\.\d+)$`)
+
+// Is the given line a section header?
+func isHeader(s string) bool {
+  return headerRe.MatchString(s)
+}
+
+// Is the given line a section footer?
+func isFooter(s string) bool {
+  return footerRe.MatchString(s)
+}
+
+// Read slice of lines from standard input.
+func getLines() []string {
+  // read from standard input
+  buf, err := io.ReadAll(os.Stdin)
+  if err != nil {
+    log.Fatal(err)
+  }
+
+  // split into lines, return result
+  return strings.Split(string(buf), "\n")
+}
+
+func main() {
+  inBody := false
+
+  // walk lines
+  for _, line := range(getLines()) {
+    if (!inBody && isHeader(line)) || (inBody && isFooter(line)) {
+      // toggle state
+      inBody = !inBody
+    } else if inBody {
+      // match digits, check for error
+      md := bodyRe.FindStringSubmatch(line)
+      if len(md) < 2 {
+        log.Fatalf("invalid body line: %s", line)
+      }
+
+      // print match to standard output
+      fmt.Println(md[1])
+    }
+  }
+}
-- 
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