chore: parse a simple jsonpath (#2566)

Also, add an ubuntu-20 reusable devcontainer.

Signed-off-by: Roman Gershman <roman@dragonflydb.io>

.devcontainer/fedora/devcontainer.json

@@ -1,5 +1,5 @@
 {
-  "name": "helio",
+  "name": "fedora30",
   "image": "ghcr.io/romange/fedora:30",
   "customizations": {
     "vscode": {

.devcontainer/ubuntu20/cmake-tools-kits.json

@@ -0,0 +1,10 @@
+[
+  {
+    "name": "GCC x86_64-linux-gnu",
+    "compilers": {
+      "C": "gcc",
+      "CXX": "g++"
+    },
+    "isTrusted": true
+  }
+]

.devcontainer/ubuntu20/devcontainer.json

@@ -0,0 +1,21 @@
+{
+  "name": "ubuntu20",
+  "image": "ghcr.io/romange/ubuntu-dev:20",
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools",
+        "ms-vscode.cpptools-themes",
+        "twxs.cmake"
+      ],
+      "settings": {
+        "cmake.buildDirectory": "/build"
+      }
+    }
+  },
+  "mounts": [
+    "source=ubuntu20-vol,target=/build,type=volume"
+  ],
+  "postCreateCommand": ".devcontainer/ubuntu20/post-create.sh ${containerWorkspaceFolder}"
+}

.devcontainer/ubuntu20/post-create.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+containerWorkspaceFolder=$1
+git config --global --add safe.directory ${containerWorkspaceFolder}/helio
+mkdir -p /root/.local/share/CMakeTools
+cp ${containerWorkspaceFolder}/.devcontainer/ubuntu20/cmake-tools-kits.json /root/.local/share/CMakeTools/

src/core/json/jsonpath_grammar.y

@@ -45,12 +45,15 @@ using namespace std;
 
 %token
   LBRACKET "["
+  RBRACKET "]"
   ROOT "$"
   DOT  "."
+  WILDCARD "*"
 
 // Needed 0 at the end to satisfy bison 3.5.1
 %token YYEOF 0
-%token <std::string> UNQ_STR "unq_str"
+%token <std::string> UNQ_STR "unquoted string"
+%token <unsigned>    UINT "integer"
 
 %%
 // Based on the following specification:
@@ -60,14 +63,21 @@ jsonpath: ROOT
         | ROOT relative_location
 
 relative_location: DOT relative_path
+        | LBRACKET bracket_expr RBRACKET
 
-relative_path: identifier
+relative_path: identifier opt_relative_location
-        | identifier relative_location
+        | WILDCARD opt_relative_location
 
-identifier: unquoted_string
+opt_relative_location:
+        | relative_location
+
+identifier: UNQ_STR
          // | single_quoted_string | double_quoted_string
 
-unquoted_string : UNQ_STR
+bracket_expr: WILDCARD
+            | index_expr
+
+index_expr: UINT
 
 %%
 

src/core/json/jsonpath_lexer.lex

@@ -5,7 +5,8 @@
 
 
 %{
-  // SECOND SECTION
+  #include <absl/strings/numbers.h>
+  #include "base/logging.h"
 %}
 
 %o bison-cc-namespace="dfly.json" bison-cc-parser="Parser"
@@ -41,6 +42,14 @@
 
 "$"         return Parser::make_ROOT(loc());
 "."         return Parser::make_DOT(loc());
+"["         return Parser::make_LBRACKET(loc());
+"]"         return Parser::make_RBRACKET(loc());
+"*"         return Parser::make_WILDCARD(loc());
+[0-9]{1,9}  {
+              unsigned val;
+              CHECK(absl::SimpleAtoi(str(), &val));
+              return Parser::make_UINT(val, loc());
+            }
 \w[\w_\-]*  return Parser::make_UNQ_STR(str(), loc());
 <<EOF>>     printf("EOF%s\n", matcher().text());
 %%

src/core/json/jsonpath_test.cc

@@ -31,21 +31,28 @@ class JsonPathTest : public ::testing::Test {
 #define NEXT_TOK(tok_enum)                                    \
   {                                                           \
     auto tok = Lex();                                         \
-    ASSERT_EQ(tok.type_get(), Parser::token::TOK_##tok_enum); \
+    ASSERT_EQ(Parser::token::TOK_##tok_enum, tok.type_get()); \
   }
 
 #define NEXT_EQ(tok_enum, type, val)                          \
   {                                                           \
     auto tok = Lex();                                         \
-    ASSERT_EQ(tok.type_get(), Parser::token::TOK_##tok_enum); \
+    ASSERT_EQ(Parser::token::TOK_##tok_enum, tok.type_get()); \
     EXPECT_EQ(val, tok.value.as<type>());                     \
   }
 
 TEST_F(JsonPathTest, Scanner) {
-  SetInput("$.мага-зин2.book[0].title");
+  SetInput("$.мага-зин2.book[0].*");
   NEXT_TOK(ROOT);
   NEXT_TOK(DOT);
   NEXT_EQ(UNQ_STR, string, "мага-зин2");
+  NEXT_TOK(DOT);
+  NEXT_EQ(UNQ_STR, string, "book");
+  NEXT_TOK(LBRACKET);
+  NEXT_EQ(UINT, unsigned, 0);
+  NEXT_TOK(RBRACKET);
+  NEXT_TOK(DOT);
+  NEXT_TOK(WILDCARD);
 }
 
 }  // namespace dfly::json