Preserve initial whitespace

Author: Mirko-von-Leipzig

scripts/reflow.awk

@@ -1,108 +1,92 @@
-# ZERO-REGEX VERSION — preserves indentation for merged comment lines
+# Merge Rust comment lines while preserving:
+# - original spacing after //, ///, //! 
+# - empty lines
+# - === headings
+# - bullets / numbered lists
+# - fenced code blocks
+# - Markdown headings
 
 function ltrim(s) {
-    while (substr(s,1,1) == " " || substr(s,1,1) == "\t")
-        s = substr(s,2)
+    while (substr(s,1,1)==" " || substr(s,1,1)=="\t") s=substr(s,2)
     return s
 }
 
-function leading_spaces(s,    i, count, c) {
-    count=0
-    for (i=1; i<=length(s); i++) {
-        c=substr(s,i,1)
-        if (c==" " || c=="\t") count++
-        else break
-    }
-    return count
-}
-
-function is_numbered_list(s,    i, c) {
+function is_numbered_list(s,    i,c) {
     found_digit=0
-    for (i=1; i<=length(s); i++) {
+    for(i=1;i<=length(s);i++){
         c=substr(s,i,1)
-        if (c >= "0" && c <= "9") { found_digit=1; continue }
-        if (found_digit && (c=="." || c==")")) return 1
+        if(c>="0" && c<="9"){found_digit=1; continue}
+        if(found_digit && (c=="."||c==")")) return 1
         return 0
     }
     return 0
 }
 
 {
-    line = $0
+    line=$0
 
-    # ---------- Detect comment type ----------
-    if (substr(line,1,3) == "///")
-        type = "doc"
-    else if (substr(line,1,3) == "//!")
-        type = "innerdoc"
-    else if (substr(line,1,2) == "//")
-        type = "line"
-    else
-        type = "none"
+    # Detect comment type
+    if(substr(line,1,3)=="///") type="doc"
+    else if(substr(line,1,3)=="//!") type="innerdoc"
+    else if(substr(line,1,2)=="//") type="line"
+    else type="none"
 
-    # ---------- Handle comment lines ----------
-    if (type != "none") {
+    if(type!="none"){
+        if(type=="doc") prefix="///"
+        else if(type=="innerdoc") prefix="//!"
+        else prefix="//"
 
-        prefix = (type=="doc" ? "///" : type=="innerdoc" ? "//!" : "//")
-        raw = substr(line, length(prefix)+1)
-        trimmed = ltrim(raw)
+        raw=substr(line,length(prefix)+1)
+        # Capture the original spaces after prefix
+        match_space=""
+        i=1
+        while(i<=length(raw) && (substr(raw,i,1)==" " || substr(raw,i,1)=="\t")){ match_space = match_space substr(raw,i,1); i++ }
+        text=substr(raw,i)
 
-        # Track indentation
-        indent = leading_spaces(raw)
+        trimmed=ltrim(raw)
 
         # ---------- Fenced code block ----------
-        if (substr(trimmed,1,3) == "```") {
-            if (in_comment) { print out_prefix merged; in_comment=0 }
-            if (fenced==0) fenced=1; else fenced=0
+        if(substr(trimmed,1,3)=="```"){
+            if(in_comment){ print out_prefix merged; in_comment=0; out_space="" }
+            if(fenced==0) fenced=1; else fenced=0
             print line
             next
         }
-        if (fenced==1) { print line; next }
+        if(fenced==1){ print line; next }
 
-        # ---------- Empty comment line ----------
+        # ---------- Empty line ----------
         empty=1
-        for (i=1; i<=length(trimmed); i++) {
-            c=substr(trimmed,i,1)
-            if (c!=" " && c!="\t") { empty=0; break }
-        }
-        if (empty) { if (in_comment) { print out_prefix merged; in_comment=0 } print line; next }
+        for(j=1;j<=length(trimmed);j++){c=substr(trimmed,j,1); if(c!=" " && c!="\t"){empty=0; break}}
+        if(empty){ if(in_comment){print out_prefix merged; in_comment=0; out_space=""} print line; next }
 
-        # ---------- === section line ----------
-        if (substr(trimmed,1,3) == "===") { if (in_comment) { print out_prefix merged; in_comment=0 } print line; next }
+        # ---------- === heading ----------
+        if(substr(trimmed,1,3)=="==="){ if(in_comment){print out_prefix merged; in_comment=0; out_space=""} print line; next }
 
         # ---------- Markdown heading ----------
-        if (substr(trimmed,1,1) == "#") { if (in_comment) { print out_prefix merged; in_comment=0 } print line; next }
+        if(substr(trimmed,1,1)=="#"){ if(in_comment){print out_prefix merged; in_comment=0; out_space=""} print line; next }
 
         # ---------- Bullet or numbered list ----------
-        first = substr(trimmed,1,1)
-        if (first=="*" || first=="-" || is_numbered_list(trimmed)) { if (in_comment) { print out_prefix merged; in_comment=0 } print line; next }
+        first=substr(trimmed,1,1)
+        if(first=="*" || first=="-" || is_numbered_list(trimmed)){ if(in_comment){print out_prefix merged; in_comment=0; out_space=""} print line; next }
 
         # ---------- Mergeable line ----------
-        if (in_comment && type==last_type) {
-            merged = merged " " ltrim(raw)  # preserve relative spacing inside line
-            if (indent < out_indent) out_indent = indent
+        if(in_comment && type==last_type){
+            merged=merged " " text
         } else {
-            if (in_comment) print out_prefix merged
+            if(in_comment) print out_prefix merged
             in_comment=1
             last_type=type
-            merged = ltrim(raw)
-            out_prefix = prefix
-            out_indent = indent
+            merged=text
+            out_prefix = prefix match_space
         }
 
         next
     }
 
-    # ---------- Non-comment line ----------
-    if (in_comment) {
-        # Apply preserved indentation
-        printf "%s%*s%s\n", out_prefix, out_indent, "", merged
-        in_comment=0
-    }
+    # Non-comment line
+    if(in_comment){ print out_prefix merged; in_comment=0; out_space="" }
     print line
 }
 
-END {
-    if (in_comment) printf "%s%*s%s\n", out_prefix, out_indent, "", merged
-}
+END { if(in_comment) print out_prefix merged }