From ea1018a0cbeebd622c7a556f10ea7363aed58dd1 Mon Sep 17 00:00:00 2001
From: "Eric S. Raymond" <esr@thyrsus.com>
Date: Tue, 1 Sep 2009 02:08:45 +0000
Subject: Split into spec translation and generation.

---
 jsongen.py | 131 ++++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 82 insertions(+), 49 deletions(-)

(limited to 'jsongen.py')

diff --git a/jsongen.py b/jsongen.py
index d684b6fb..ff736e0e 100755
--- a/jsongen.py
+++ b/jsongen.py
@@ -11,41 +11,75 @@ import sys, getopt
 
 # Make shared field names to data types 
 typemap = {
-    # AIS fields
     "raim":"boolean",
     "accuracy":"boolean",
     "timestamp":"string",
     }
 
-# Map C and Python-type format letters to JSON parser datatypes 
-fmtmap = {
-    "d": "integer",
-    "u": "uinteger",
-    "f": "real",
-    "a": "string",
-    }
-
-
 ais_specs = (
-    ("json_ais4", "\tAIS_HEADER,", "ais->type4",
-     "\"timestamp\":\"%4u:%02u:%02uT%02u:%02u:%02uZ\","\
-     "\"accuracy\":%s,\"lon\":%d,\"lat\":%d,"\
-     "\"epfd\":%u,\"raim\":%s,\"radio\":%d}\r\n"
-     ),
-    )
+    {
+    "initname" : "json_ais4",
+    "header": "\tAIS_HEADER,",
+    "structname": "ais->type4",
+    "fieldmap":(
+        # fieldname   type        default
+        ('timestamp', 'string',   None),
+        ('accuracy',  'boolean',  "true"),
+        ('lon',       'integer',  "AIS_LON_NOT_AVAILABLE"),
+        ('lat',       'integer',  "AIS_LAT_NOT_AVAILABLE"),
+        ('epfd',      'uinteger', "0"),
+        ('raim',      'boolean',  "false"),
+        ('radio',     'integer',  "0"),
+        ),
+    "stringbuffered":("timestamp",),
+    },
+)
     
-def generate(initname, header, structname, specifier):
-    specifier = specifier.strip()
-    if specifier[-1] == "}":
-        specifier = specifier[:-1]
+def generate(spec):
+    print "    const struct json_attr_t %s[] = {" % spec["initname"]
+    if spec["header"]:
+        print spec["header"]
+    for (attr, itype, default) in spec["fieldmap"]:
+        structname = spec["structname"]
+        if itype == "string":
+            deref = ""
+        else:
+            deref = "&"
+        if attr in spec["stringbuffered"]:
+            target = attr
+        else:
+            target = structname + "." + attr
+        print '\t{"%s",%s%s,%s.addr.%s = %s%s,' % \
+               (attr, " "*(12-len(attr)),itype, " "*(12-len(itype)), itype, deref, target)
+        leader = " " * 37
+        if itype == "string":
+            print leader + ".maxlen = sizeof(%s)}," % target
+        else:
+            print leader + ".dflt.%s = %s}," % (itype, default)
+
+    print """\
+	{NULL},
+    };
+
+"""
+
+def string_to_specifier(strspec):
+    "Compile a Python-style format string to an attribute-type fieldmap."
+    # Map C and Python-type format letters to JSON parser datatypes 
+    fmtmap = {
+        "d": "integer",
+        "u": "uinteger",
+        "f": "real",
+        "a": "string",
+        }
+    strspec = strspec.strip()
+    if strspec[-1] == "}":
+        strspec = strspec[:-1]
     else:
         print "Missing terminating }"
         sys.exit(1)
-
-    print "    const struct json_attr_t %s[] = {" % initname
-    if header:
-        print header
-    for item in specifier.split(","):
+    print '"fieldmap":('
+    for item in strspec.split(","):
         if "timestamp" in item:
             (attr, itype) = ("timestamp", "string")
         else:
@@ -59,31 +93,30 @@ def generate(initname, header, structname, specifier):
                 itype = typemap[attr]
             if fmt[-1] in fmtmap:
                 itype = fmtmap[fmt[-1]]
-        if itype == "string":
-            deref = ""
-        else:
-            deref = "&"
-        print '\t{"%s",%s%s,%s.addr.%s = %s%s.%s,' % \
-               (attr, " "*(12-len(attr)),itype, " "*(12-len(itype)), itype, deref, structname, attr)
-        leader = " " * 37
-        if itype == "string":
-            print leader + ".maxlen = sizeof(%s.%s)}," % (structname, attr)
-        elif itype == "boolean":
-            print leader + ".dflt.boolean = false},"
-        elif itype == "real":
-            print leader + ".dflt.real = 0.0},"
-        else:
-            print leader + ".dflt.%s = 0}," % itype
+        print "    " + `(attr, itype)` + ","
+    print "    )"
 
-    print """\
-	{NULL},
-    };
 
-"""
+# Edit into this global the string spec you need to convert
+stringspec = \
+"\"timestamp\":\"%4u:%02u:%02uT%02u:%02u:%02uZ\","\
+     "\"accuracy\":%s,\"lon\":%d,\"lat\":%d,"\
+     "\"epfd\":%u,\"raim\":%s,\"radio\":%d}\r\n"
 
 if __name__ == '__main__':
-    for description in ais_specs:
-        generate(initname=description[0],
-                 header=description[1],
-                 structname=description[2],
-                 specifier=description[3])
+    try:
+        (options, arguments) = getopt.getopt(sys.argv[1:], "g")
+    except getopt.GetoptError, msg:
+        print "jsongen.py: " + str(msg)
+        raise SystemExit, 1
+
+    specify = False
+    for (switch, val) in options:
+        if (switch == '-g'):
+            specify = True
+
+    if specify:
+        string_to_specifier(stringspec)
+    else:
+        for description in ais_specs:
+            generate(description)
-- 
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