Merge pull request #288 from tr11/json-parser

Json parser

cobol-parser/src/main/scala/za/co/absa/cobrix/cobol/parser/antlr/ParserJson.scala

@@ -0,0 +1,125 @@
+/*
+ * Copyright 2018 ABSA Group Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package za.co.absa.cobrix.cobol.parser.antlr
+import org.antlr.v4.runtime.{BailErrorStrategy, CharStreams, CommonTokenStream}
+
+import scala.collection.JavaConversions._
+
+
+class ParserJson {
+  def parse(text: String): Any = {
+    val visitor = new ParserJsonVisitor()
+    val charStream = CharStreams.fromString(text)
+    val lexer = new jsonLexer(charStream)
+    val tokens = new CommonTokenStream(lexer)
+    val parser = new jsonParser(tokens)
+    parser.setErrorHandler(new BailErrorStrategy());
+    visitor.visit(parser.json())
+  }
+
+  def parseMap(text: String): Map[String, Any] = {
+    this.parse(text).asInstanceOf[Map[String, Any]]
+  }
+}
+
+
+class ParserJsonVisitor extends jsonBaseVisitor[Any] {
+  /**
+   * Visit a parse tree produced by {@link jsonParser#pair}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitPair(ctx: jsonParser.PairContext): Any = {
+    val key = ctx.STRING().getText
+    val value = this.visit(ctx.value)
+    (key.substring(1, key.length - 1), value)
+  }
+
+  /**
+   * Visit a parse tree produced by the {@code value_string}
+   * labeled alternative in {@link jsonParser#value}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitValue_string(ctx: jsonParser.Value_stringContext): Any = {
+    val text = ctx.getText
+    text.substring(1, text.length - 1)
+  }
+
+  /**
+   * Visit a parse tree produced by the {@code value_number}
+   * labeled alternative in {@link jsonParser#value}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitValue_number(ctx: jsonParser.Value_numberContext): Any = {
+    val text = ctx.getText
+    try { text.toInt } catch { case _: Throwable => text.toDouble }
+  }
+
+  /**
+   * Visit a parse tree produced by the {@code value_obj}
+   * labeled alternative in {@link jsonParser#value}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitValue_obj(ctx: jsonParser.Value_objContext): Any = {
+    ctx.obj().pair().map(x => this.visit(x).asInstanceOf[(String, Any)]).toMap
+  }
+
+  /**
+   * Visit a parse tree produced by the {@code value_array}
+   * labeled alternative in {@link jsonParser#value}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitValue_array(ctx: jsonParser.Value_arrayContext): Any = {
+    ctx.arr.value.map(x => this.visit(x)).toArray
+  }
+
+  /**
+   * Visit a parse tree produced by the {@code value_true}
+   * labeled alternative in {@link jsonParser#value}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitValue_true(ctx: jsonParser.Value_trueContext): Any = true
+
+  /**
+   * Visit a parse tree produced by the {@code value_false}
+   * labeled alternative in {@link jsonParser#value}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitValue_false(ctx: jsonParser.Value_falseContext): Any = false
+
+  /**
+   * Visit a parse tree produced by the {@code value_null}
+   * labeled alternative in {@link jsonParser#value}.
+   *
+   * @param ctx the parse tree
+   * @return the visitor result
+   */
+  override def visitValue_null(ctx: jsonParser.Value_nullContext): Any = null
+}

cobol-parser/src/main/scala/za/co/absa/cobrix/cobol/parser/antlr/json.g4

@@ -0,0 +1,77 @@
+
+grammar json;
+
+json
+   : value
+   ;
+
+obj
+   : '{' pair (',' pair)* '}'
+   | '{' '}'
+   ;
+
+pair
+   : STRING ':' value
+   ;
+
+arr
+   : '[' value (',' value)* ']'
+   | '[' ']'
+   ;
+
+value
+   : STRING         #value_string
+   | NUMBER         #value_number
+   | obj            #value_obj
+   | arr            #value_array
+   | 'true'         #value_true
+   | 'false'        #value_false
+   | 'null'         #value_null
+   ;
+
+
+STRING
+   : '"' (ESC | SAFECODEPOINT)* '"'
+   ;
+
+
+fragment ESC
+   : '\\' (["\\/bfnrt] | UNICODE)
+   ;
+
+
+fragment UNICODE
+   : 'u' HEX HEX HEX HEX
+   ;
+
+
+fragment HEX
+   : [0-9a-fA-F]
+   ;
+
+
+fragment SAFECODEPOINT
+   : ~ ["\\\u0000-\u001F]
+   ;
+
+
+NUMBER
+   : '-'? INT ('.' [0-9] +)? EXP?
+   ;
+
+
+fragment INT
+   : '0' | [1-9] [0-9]*
+   ;
+
+// no leading zeros
+
+fragment EXP
+   : [Ee] [+\-]? INT
+   ;
+
+// \- since - means "range" inside [...]
+
+WS
+   : [ \t\n\r] + -> skip
+   ;

cobol-parser/src/main/scala/za/co/absa/cobrix/cobol/parser/antlr/jsonBaseVisitor.java

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2018 ABSA Group Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+package za.co.absa.cobrix.cobol.parser.antlr;
+
+// Generated from json.g4 by ANTLR 4.7.2
+import org.antlr.v4.runtime.tree.AbstractParseTreeVisitor;
+
+/**
+ * This class provides an empty implementation of {@link jsonVisitor},
+ * which can be extended to create a visitor which only needs to handle a subset
+ * of the available methods.
+ *
+ * @param <T> The return type of the visit operation. Use {@link Void} for
+ * operations with no return type.
+ */
+public class jsonBaseVisitor<T> extends AbstractParseTreeVisitor<T> implements jsonVisitor<T> {
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitJson(jsonParser.JsonContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitObj(jsonParser.ObjContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitPair(jsonParser.PairContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitArr(jsonParser.ArrContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitValue_string(jsonParser.Value_stringContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitValue_number(jsonParser.Value_numberContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitValue_obj(jsonParser.Value_objContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitValue_array(jsonParser.Value_arrayContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitValue_true(jsonParser.Value_trueContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitValue_false(jsonParser.Value_falseContext ctx) { return visitChildren(ctx); }
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation returns the result of calling
+	 * {@link #visitChildren} on {@code ctx}.</p>
+	 */
+	@Override public T visitValue_null(jsonParser.Value_nullContext ctx) { return visitChildren(ctx); }
+}