[sql] add json_group_object aggregate function

NEWS

@@ -4,6 +4,8 @@ lnav v0.8.1:
      * Log formats can now create SQL views and execute other statements
        by adding '.sql' files to their format directories.  The SQL scripts
        will be executed on startup.
+     * Added a 'json_group_object' aggregate SQL function that collects values
+       from a GROUP BY query into an JSON object.
 
      Interface Changes:
      * The 'o/O' hotkeys have been reassigned to navigate through log

configure.ac

@@ -39,8 +39,8 @@ AC_PROG_CXX
 
 CPPFLAGS="$CPPFLAGS -D_ISOC99_SOURCE -D__STDC_LIMIT_MACROS"
 
-# CFLAGS=`echo $CFLAGS | sed 's/-O2//g'`
-# CXXFLAGS=`echo $CXXFLAGS | sed 's/-O2//g'`
+CFLAGS=`echo $CFLAGS | sed 's/-O2//g'`
+CXXFLAGS=`echo $CXXFLAGS | sed 's/-O2//g'`
 
 AC_ARG_VAR(SFTP_TEST_URL)
 

docs/source/conf.py

@@ -49,7 +49,7 @@ master_doc = 'index'
 
 # General information about the project.
 project = u'lnav'
-copyright = u'2014, Tim Stack'
+copyright = u'2015, Tim Stack'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the

docs/source/sqlext.rst

@@ -139,6 +139,18 @@ Network information functions:
 * gethostbyaddr - Convert an IPv4/IPv6 address into a host name.  If the
   reverse lookup fails, the input value will be returned.
 
+JSON
+----
+
+JSON functions:
+
+* jget(json, json_ptr) - Get the value from the JSON-encoded string in
+  first argument that is referred to by the
+  `JSON-Pointer <https://tools.ietf.org/html/rfc6901>`_ in the second.
+* json_group_array(key0, value0, ... keyN, valueN) - An aggregate function
+  that creates a JSON-encoded object from the key value pairs given as
+  arguments.
+
 Time
 ----
 

src/json-extension-functions.cc

@@ -212,17 +212,111 @@ static void sql_jget(sqlite3_context *context,
     sqlite3_result_text(context, result.c_str(), result.size(), SQLITE_TRANSIENT);
 }
 
+struct json_agg_context {
+    yajl_gen_t *jac_yajl_gen;
+};
+
+static void sql_json_group_object_step(sqlite3_context *context,
+                                       int argc,
+                                       sqlite3_value **argv)
+{
+    if ((argc % 2) == 1) {
+        sqlite3_result_error(
+                context,
+                "Uneven number of arguments to json_group_object(), "
+                        "expecting key and value pairs",
+                -1);
+        return;
+    }
+
+    json_agg_context *jac = (json_agg_context *) sqlite3_aggregate_context(
+            context, sizeof(json_agg_context));
+
+
+    if (jac->jac_yajl_gen == NULL) {
+        jac->jac_yajl_gen = yajl_gen_alloc(NULL);
+        yajl_gen_config(jac->jac_yajl_gen, yajl_gen_beautify, false);
+
+        yajl_gen_map_open(jac->jac_yajl_gen);
+    }
+
+    for (int lpc = 0; (lpc + 1) < argc; lpc += 2) {
+        if (sqlite3_value_type(argv[lpc]) == SQLITE_NULL) {
+            continue;
+        }
+
+        const unsigned char *key = sqlite3_value_text(argv[lpc]);
+
+        yajl_gen_string(jac->jac_yajl_gen, key, strlen((const char *) key));
+
+        switch (sqlite3_value_type(argv[lpc + 1])) {
+            case SQLITE_NULL:
+                yajl_gen_null(jac->jac_yajl_gen);
+                break;
+            case SQLITE3_TEXT: {
+                const unsigned char *value = sqlite3_value_text(argv[lpc + 1]);
+
+                yajl_gen_string(jac->jac_yajl_gen,
+                                value,
+                                strlen((const char *) value));
+                break;
+            }
+            case SQLITE_INTEGER: {
+                const unsigned char *value = sqlite3_value_text(argv[lpc + 1]);
+
+                yajl_gen_number(jac->jac_yajl_gen,
+                                (const char *) value,
+                                strlen((const char *) value));
+                break;
+            }
+            case SQLITE_FLOAT: {
+                double value = sqlite3_value_double(argv[lpc + 1]);
+
+                yajl_gen_double(jac->jac_yajl_gen, value);
+                break;
+            }
+        }
+    }
+
+}
+
+static void sql_json_group_object_final(sqlite3_context *context)
+{
+    json_agg_context *jac = (json_agg_context *) sqlite3_aggregate_context(
+            context, 0);
+
+    if (jac == NULL) {
+        sqlite3_result_text(context, "{}", -1, SQLITE_STATIC);
+    }
+    else {
+        const unsigned char *buf;
+        size_t len;
+
+        yajl_gen_map_close(jac->jac_yajl_gen);
+        yajl_gen_get_buf(jac->jac_yajl_gen, &buf, &len);
+        sqlite3_result_text(context, (const char *) buf, len, SQLITE_TRANSIENT);
+        yajl_gen_free(jac->jac_yajl_gen);
+    }
+}
+
 int json_extension_functions(const struct FuncDef **basic_funcs,
                              const struct FuncDefAgg **agg_funcs)
 {
-    static const struct FuncDef fs_funcs[] = {
+    static const struct FuncDef json_funcs[] = {
         { "jget",  -1, 0, SQLITE_UTF8, 0, sql_jget },
 
         { NULL }
     };
 
-    *basic_funcs = fs_funcs;
-    *agg_funcs   = NULL;
+    static const struct FuncDefAgg json_agg_funcs[] = {
+            { "json_group_object", -1, 0, 0,
+                    sql_json_group_object_step, sql_json_group_object_final, },
+
+            { NULL }
+    };
+
+    *basic_funcs = json_funcs;
+    *agg_funcs   = json_agg_funcs;
 
     return SQLITE_OK;
 }

test/test_sql_json_func.sh

@@ -53,3 +53,47 @@ check_output "jget for array does not work" <<EOF
 Row 0:
   Column jget('[null, true, 20, 30, 40]', '/0/foo'): (null)
 EOF
+
+run_test ./drive_sql "select json_group_object(key) from (select 1 as key)"
+
+check_error_output "" <<EOF
+error: sqlite3_exec failed -- Uneven number of arguments to json_group_object(), expecting key and value pairs
+EOF
+
+GROUP_SELECT_1=$(cat <<EOF
+SELECT id, json_group_object(key, value) as stack FROM (
+              SELECT 1 as id, 'key1' as key, 10 as value
+    UNION ALL SELECT 1 as id, 'key2' as key, 20 as value
+    UNION ALL SELECT 1 as id, 'key3' as key, 30 as value)
+EOF
+)
+
+run_test ./drive_sql "$GROUP_SELECT_1"
+
+check_error_output "" <<EOF
+EOF
+
+check_output "json_group_object does not work" <<EOF
+Row 0:
+  Column         id: 1
+  Column      stack: {"key1":10,"key2":20,"key3":30}
+EOF
+
+GROUP_SELECT_2=$(cat <<EOF
+SELECT id, json_group_object(key, value) as stack FROM (
+              SELECT 1 as id, 1 as key, 10 as value
+    UNION ALL SELECT 1 as id, 2 as key, null as value
+    UNION ALL SELECT 1 as id, 3 as key, 30.5 as value)
+EOF
+)
+
+run_test ./drive_sql "$GROUP_SELECT_2"
+
+check_error_output "" <<EOF
+EOF
+
+check_output "json_group_object does not work" <<EOF
+Row 0:
+  Column         id: 1
+  Column      stack: {"1":10,"2":null,"3":30.5}
+EOF