From 087a8aa41221fd5842de06b08aa5e9a790c98d7c Mon Sep 17 00:00:00 2001
From: Attila Kovacs <attipaci@gmail.com>
Date: Tue, 17 Dec 2024 17:40:12 +0100
Subject: [PATCH] Added xjsonFieldToIndentedString()

---
 README.md         |  4 ++--
 include/xchange.h | 10 ---------
 include/xjson.h   |  1 +
 src/xjson.c       | 56 +++++++++++++++++++++++++++++++++++------------
 4 files changed, 45 insertions(+), 26 deletions(-)

diff --git a/README.md b/README.md
index 95b103f..138d22f 100644
--- a/README.md
+++ b/README.md
@@ -464,12 +464,12 @@ or parse it from a file, which contains a JSON definition of the structured data
 
 ### Snippets
 
-Alternatively, you can also create partial JSON snippets for individual fields, e.g.:
+Alternatively, you can also create partial JSON fragments for individual fields, e.g.:
   
 ```c
   XField *f = ...
   
-  // Obtain a JSON string snippet of the field 'f'.
+  // Obtain a JSON fragment for the field 'f'.
   char *json = xjsonFieldToString(f);
 ```
 
diff --git a/include/xchange.h b/include/xchange.h
index ea1c0d4..81a1403 100644
--- a/include/xchange.h
+++ b/include/xchange.h
@@ -287,16 +287,6 @@ char *xStringCopyOf(const char *str);
 #  define NAN               (0.0/0.0)
 #endif
 
-#  ifndef THREAD_LOCAL
-#    if __STDC_VERSION__ >= 201112L
-#      define THREAD_LOCAL _Thread_local          ///< C11 standard for thread-local variables
-#    elif __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 3)
-#      define THREAD_LOCAL __thread               ///< pre C11 gcc >= 3.3 standard for thread-local variables
-#    else
-#      define THREAD_LOCAL                        ///< no thread-local variables
-#    endif
-#  endif
-
 int x_error(int ret, int en, const char *from, const char *desc, ...);
 int x_warn(const char *from, const char *desc, ...);
 int x_trace(const char *loc, const char *op, int n);
diff --git a/include/xjson.h b/include/xjson.h
index b107522..40eac0f 100644
--- a/include/xjson.h
+++ b/include/xjson.h
@@ -24,6 +24,7 @@ int xjsonGetIndent();
 
 char *xjsonToString(const XStructure *s);
 char *xjsonFieldToString(const XField *f);
+char *xjsonFieldToIndentedString(int indent, const XField *f);
 XStructure *xjsonParseFilename(const char *fileName, int *lineNumber);
 XStructure *xjsonParseFile(FILE *file, size_t length, int *lineNumber);
 XStructure *xjsonParseAt(char **src, int *lineNumber);
diff --git a/src/xjson.c b/src/xjson.c
index a89dda0..567bef4 100644
--- a/src/xjson.c
+++ b/src/xjson.c
@@ -152,40 +152,51 @@ char *xjsonToString(const XStructure *s) {
 
 
 /**
- * Converts an XField into its JSON representation. Conversion errors are reported to stderr
- * or the altenate stream set by xSetErrorStream().
+ * Converts an XField into its JSON representation, with the specified indentation of white spaces
+ * in front of every line. Conversion errors are reported to stderr or the altenate stream set by
+ * xSetErrorStream().
  *
- * @param f     Pointer to field
- * @return      String JSON representation, or NULL if there was an error (errno set to EINVAL).
+ * @param indent  Number of white spaces to insert in front of each line.
+ * @param f       Pointer to field
+ * @return        String JSON representation, or NULL if there was an error (errno set to EINVAL).
  *
- * @sa xjsonToString()
- * @sa xjsonSetIndent()
- * @sa xjsonParseAt()
- * @sa xjsonParseFile()
- * @sa xjsonParseFilename()
+ * @sa xjsonFieldToString()
  */
-char *xjsonFieldToString(const XField *f) {
-  char *str;
+char *xjsonFieldToIndentedString(int indent, const XField *f) {
+  static const char *fn = "xjsonFieldToIndentedString";
 
+  char *prefix, *str;
   int n;
 
   if(!f) return xStringCopyOf(JSON_NULL);
   if(!xerr) xerr = stderr;
+  if(indent < 0) indent = 0;
 
-  n = GetFieldStringSize(0, f, FALSE);
+  n = GetFieldStringSize(indent, f, FALSE);
   if(n < 0) {
     Error("%s\n", xErrorDescription(n));
     errno = EINVAL;
     return NULL;
   }
 
+  prefix = malloc(indent + 1);
+  if(!prefix) {
+    x_error(0, errno, fn, "alloc error (%d) bytes", (n + 1));
+    return NULL;
+  }
+  if(indent > 0) memset(prefix, ' ', indent);
+  prefix[indent] = '\0';
+
   str = (char *) malloc(n + 1);  // + '\0'
   if(!str) {
-    Error("Out of memory (need %ld bytes).\n", (long) (n+1));
+    x_error(0, errno, fn, "alloc error (%d) bytes", (n + 1));
+    free(prefix);
     return NULL;
   }
 
-  n = PrintField("", f, str);
+  n = PrintField(prefix, f, str);
+  free(prefix);
+
   if (n < 0) {
     free(str);
     return NULL;
@@ -194,6 +205,23 @@ char *xjsonFieldToString(const XField *f) {
   return str;
 }
 
+/**
+ * Converts an XField into its JSON representation. Conversion errors are reported to stderr
+ * or the altenate stream set by xSetErrorStream().
+ *
+ * @param f     Pointer to field
+ * @return      String JSON representation, or NULL if there was an error (errno set to EINVAL).
+ *
+ * @sa xjsonToString()
+ * @sa xjsonSetIndent()
+ * @sa xjsonParseAt()
+ * @sa xjsonParseFile()
+ * @sa xjsonParseFilename()
+ */
+char *xjsonFieldToString(const XField *f) {
+  return xjsonFieldToIndentedString(0, f);
+}
+
 /**
  * Parses a JSON object from the given parse position, returning the structured data
  * and updating the parse position. Parse errors are reported to stderr or the alternate