Refactor parser

Makefile.am

@@ -273,6 +273,7 @@ EXTRA_DIST = autogen.sh \
 	src/ocispec/generate.py \
 	src/ocispec/headers.py \
 	src/ocispec/helpers.py \
+	src/ocispec/json_api.py \
 	src/ocispec/sources.py \
 	$(HEADER_FILES) \
 	src/ocispec/read-file.h \

src/ocispec/headers.py

@@ -27,6 +27,7 @@
 # libocispec output files to be licensed under the GNU General Public
 # License without this special exception.
 import helpers
+import json_api
 
 def append_header_arr(obj, header, prefix):
     '''
@@ -60,7 +61,7 @@ def append_header_arr(obj, header, prefix):
     typename = helpers.get_name_substr(obj.name, prefix)
     header.append(f"}}\n{typename};\n\n")
     header.append(f"void free_{typename} ({typename} *ptr);\n\n")
-    header.append(f"{typename} *make_{typename} (yajl_val tree, const struct parser_context *ctx, parser_error *err);\n\n")
+    header.append(f"{typename} *make_{typename} ({json_api.VAL_TYPE} tree, const struct parser_context *ctx, parser_error *err);\n\n")
 
 
 def append_header_map_str_obj(obj, header, prefix):
@@ -164,7 +165,7 @@ def append_type_c_header(obj, header, prefix):
             else:
                 append_header_child_others(i, header, prefix)
         if obj.children is not None:
-            header.append("    yajl_val _residual;\n")
+            header.append(f"    {json_api.VAL_TYPE} _residual;\n")
         if len(present_tags) > 0:
             header.append("\n")
             for tag in present_tags:
@@ -173,8 +174,8 @@ def append_type_c_header(obj, header, prefix):
     header.append(f"}}\n{typename};\n\n")
     header.append(f"void free_{typename} ({typename} *ptr);\n\n")
     header.append(f"{typename} *clone_{typename} ({typename} *src);\n")
-    header.append(f"{typename} *make_{typename} (yajl_val tree, const struct parser_context *ctx, parser_error *err);\n\n")
-    header.append(f"yajl_gen_status gen_{typename} (yajl_gen g, const {typename} *ptr, const struct parser_context *ctx, parser_error *err);\n\n")
+    header.append(f"{typename} *make_{typename} ({json_api.VAL_TYPE} tree, const struct parser_context *ctx, parser_error *err);\n\n")
+    header.append(f"{json_api.GEN_STATUS_TYPE} gen_{typename} ({json_api.GEN_TYPE} g, const {typename} *ptr, const struct parser_context *ctx, parser_error *err);\n\n")
 
 def header_reflect_top_array(obj, prefix, header):
     c_typ = helpers.get_prefixed_pointer(obj.name, obj.subtyp, prefix) or \

src/ocispec/json_api.py

@@ -0,0 +1,234 @@
+# -*- coding: utf-8 -*-
+#
+# libocispec - a C library for parsing OCI spec files.
+#
+# Copyright (C) 2017, 2019 Giuseppe Scrivano <giuseppe@scrivano.org>
+# libocispec is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# libocispec is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with libocispec.  If not, see <http://www.gnu.org/licenses/>.
+#
+# As a special exception, you may create a larger work that contains
+# part or all of the libocispec parser skeleton and distribute that work
+# under terms of your choice, so long as that work isn't itself a
+# parser generator using the skeleton or a modified version thereof
+# as a parser skeleton.  Alternatively, if you modify or redistribute
+# the parser skeleton itself, you may (at your option) remove this
+# special exception, which will cause the skeleton and the resulting
+# libocispec output files to be licensed under the GNU General Public
+# License without this special exception.
+
+"""
+JSON library abstraction for C code generation.
+
+All JSON library-specific C code fragments are centralized in this module.
+To switch to a different JSON library, modify this module only -- the rest
+of the generator uses these names and helpers exclusively.
+"""
+
+# ---------------------------------------------------------------------------
+# C type names
+# ---------------------------------------------------------------------------
+VAL_TYPE = "yajl_val"
+GEN_TYPE = "yajl_gen"
+GEN_STATUS_TYPE = "yajl_gen_status"
+GEN_STATUS_OK = "yajl_gen_status_ok"
+
+# ---------------------------------------------------------------------------
+# Type constants passed to get_val()
+# ---------------------------------------------------------------------------
+TYPE_STRING = "yajl_t_string"
+TYPE_NUMBER = "yajl_t_number"
+TYPE_OBJECT = "yajl_t_object"
+TYPE_ARRAY = "yajl_t_array"
+TYPE_TRUE = "yajl_t_true"
+TYPE_FALSE = "yajl_t_false"
+
+# ---------------------------------------------------------------------------
+# Value extraction -- each returns a C expression string
+# ---------------------------------------------------------------------------
+
+def get_string(val):
+    return f"YAJL_GET_STRING ({val})"
+
+def get_number(val):
+    return f"YAJL_GET_NUMBER ({val})"
+
+def is_number(val):
+    return f"YAJL_IS_NUMBER ({val})"
+
+def is_true(val):
+    return f"YAJL_IS_TRUE ({val})"
+
+# ---------------------------------------------------------------------------
+# Array access -- each returns a C expression string
+# ---------------------------------------------------------------------------
+
+def array_check(val):
+    return f"YAJL_GET_ARRAY ({val}) != NULL"
+
+def array_len(val):
+    return f"YAJL_GET_ARRAY_NO_CHECK ({val})->len"
+
+def array_get(val, idx):
+    return f"YAJL_GET_ARRAY_NO_CHECK ({val})->values[{idx}]"
+
+def array_values(val):
+    return f"YAJL_GET_ARRAY_NO_CHECK ({val})->values"
+
+# ---------------------------------------------------------------------------
+# Object access -- each returns a C expression string
+# ---------------------------------------------------------------------------
+
+def object_check(val):
+    return f"YAJL_GET_OBJECT ({val}) != NULL"
+
+def object_len(val):
+    return f"YAJL_GET_OBJECT_NO_CHECK ({val})->len"
+
+def object_keys(val):
+    return f"YAJL_GET_OBJECT_NO_CHECK ({val})->keys"
+
+def object_values(val):
+    return f"YAJL_GET_OBJECT_NO_CHECK ({val})->values"
+
+# ---------------------------------------------------------------------------
+# Internal structure access (for residual handling)
+# ---------------------------------------------------------------------------
+
+def object_type_field(var):
+    return f"{var}->type"
+
+def object_type_value():
+    return TYPE_OBJECT
+
+def set_object_type(var):
+    return f"{var}->type = {TYPE_OBJECT}"
+
+def object_keys_field(var):
+    return f"{var}->u.object.keys"
+
+def object_values_field(var):
+    return f"{var}->u.object.values"
+
+def alloc_object_keys(var, count):
+    return f"{var}->u.object.keys = calloc ({count}, sizeof (const char *))"
+
+def alloc_object_values(var, count):
+    return f"{var}->u.object.values = calloc ({count}, sizeof ({VAL_TYPE}))"
+
+def object_key_direct(var, idx):
+    return f"{var}->u.object.keys[{idx}]"
+
+def object_value_direct(var, idx):
+    return f"{var}->u.object.values[{idx}]"
+
+def object_len_field(var):
+    return f"{var}->u.object.len"
+
+# ---------------------------------------------------------------------------
+# Generation -- each returns a C expression string
+# ---------------------------------------------------------------------------
+
+def gen_string(gen, str_expr, len_expr):
+    return f"yajl_gen_string (({GEN_TYPE}) {gen}, (const unsigned char *)({str_expr}), {len_expr})"
+
+def gen_bool(gen, val):
+    return f"yajl_gen_bool (({GEN_TYPE}){gen}, (int)({val}))"
+
+def gen_double(gen, val):
+    return f"yajl_gen_double (({GEN_TYPE}){gen}, {val})"
+
+def gen_map_open(gen):
+    return f"yajl_gen_map_open (({GEN_TYPE}) {gen})"
+
+def gen_map_close(gen):
+    return f"yajl_gen_map_close (({GEN_TYPE}) {gen})"
+
+def gen_array_open(gen):
+    return f"yajl_gen_array_open (({GEN_TYPE}) {gen})"
+
+def gen_array_close(gen):
+    return f"yajl_gen_array_close (({GEN_TYPE}) {gen})"
+
+# ---------------------------------------------------------------------------
+# Configuration
+# ---------------------------------------------------------------------------
+GEN_BEAUTIFY = "yajl_gen_beautify"
+
+def gen_config(gen, option, val):
+    return f"yajl_gen_config ({gen}, {option}, {val})"
+
+# ---------------------------------------------------------------------------
+# Buffer access and cleanup
+# ---------------------------------------------------------------------------
+
+def gen_get_buf(gen, buf_var, len_var):
+    return f"yajl_gen_get_buf ({gen}, {buf_var}, {len_var})"
+
+def gen_clear(gen):
+    return f"yajl_gen_clear ({gen})"
+
+def gen_free(gen):
+    return f"yajl_gen_free ({gen})"
+
+# ---------------------------------------------------------------------------
+# Parsing and lifecycle
+# ---------------------------------------------------------------------------
+
+def tree_parse(data, buf, size):
+    return f"yajl_tree_parse ({data}, {buf}, {size})"
+
+TREE_FREE_FUNC = "yajl_tree_free"
+
+def tree_free(val):
+    return f"{TREE_FREE_FUNC} ({val})"
+
+# ---------------------------------------------------------------------------
+# Residual serialization
+# ---------------------------------------------------------------------------
+GEN_RESIDUAL_FUNC = "gen_yajl_object_residual"
+
+def gen_residual(obj, gen, err):
+    return f"{GEN_RESIDUAL_FUNC} ({obj}, {gen}, {err})"
+
+# ---------------------------------------------------------------------------
+# Prologue defines needed at the top of each generated .c file
+# ---------------------------------------------------------------------------
+
+def get_prologue_defines():
+    return [
+        "#define YAJL_GET_ARRAY_NO_CHECK(v) (&(v)->u.array)\n",
+        "#define YAJL_GET_OBJECT_NO_CHECK(v) (&(v)->u.object)\n",
+    ]
+
+# ---------------------------------------------------------------------------
+# Cleanup helpers emitted once per generated .c file (epilog)
+# ---------------------------------------------------------------------------
+
+def get_gen_cleanup_block():
+    """Return the static cleanup function for the JSON generator."""
+    return f"""\
+static void
+cleanup_{GEN_TYPE} ({GEN_TYPE} g)
+{{
+    if (!g)
+      return;
+    {gen_clear('g')};
+    {gen_free('g')};
+}}
+
+define_cleaner_function ({GEN_TYPE}, cleanup_{GEN_TYPE})
+"""
+
+def get_val_cleaner_define():
+    """Return the cleaner macro for the JSON value tree."""
+    return f"define_cleaner_function ({VAL_TYPE}, {TREE_FREE_FUNC})"