Support the new line character in windows

ballerina/modules/lexer/scan.bal

@@ -158,7 +158,7 @@ isolated function scanPlanarChar(LexerState state) returns boolean|LexicalError
     }
 
     // Step back from the white spaces if EOL or ':' is reached 
-    if state.peek() == () || state.peek() == "\n" {
+    if state.peek() == () || state.isNewLine() {
         state.forward(-numWhitespace);
         return true;
     }

ballerina/modules/lexer/state.bal

@@ -164,4 +164,10 @@ public class LexerState {
     }
 
     public isolated function isFlowCollection() returns boolean => self.numOpenedFlowCollections > 0;
+
+    # Check if the current character is a new line. 
+    # This should be replaced by the os module once it supports an API: #4931.
+    # 
+    # + return - True if the current character is a new line
+    public isolated function isNewLine() returns boolean => self.peek() == "\n" || self.peek() == "\r\n";
 }

ballerina/modules/parser/state.bal

@@ -89,7 +89,7 @@ public class ParserState {
         if self.lineIndex >= self.numLines {
             return generateGrammarError(self, message);
         }
-        string[] lines = <string[]>self.lines;
+        string[] lines = self.lines;
         line = lines[self.lineIndex];
 
         self.explicitDoc = false;

ballerina/tests/api_test.bal

@@ -17,8 +17,7 @@ import ballerina/io;
 import ballerina/test;
 
 @test:Config {
-    groups: ["api"],
-    enable: false
+    groups: ["api"]
 }
 function testReadYamlString() returns error? {
     string input = string `
@@ -76,8 +75,7 @@ function testWriteYamlFile() returns error? {
 
 @test:Config {
     dataProvider: yamlSchemaDataGen,
-    groups: ["api"],
-    enable: false
+    groups: ["api"]
 }
 function testReadYAMLSchema(YAMLSchema schema, json expectedOutput) returns error? {
     string input = string `

ballerina/yaml.bal

@@ -22,9 +22,9 @@ import yaml.serializer;
 # + config - Configuration for reading a YAML file
 # + return - YAML map object on success. Else, returns an error
 public isolated function readString(string yamlString, *ReadConfig config) returns json|Error {
-    io:ReadableByteChannel readableChannel = check io:createReadableChannel(yamlString.toBytes());
-    io:ReadableCharacterChannel readableCharChannel = new (readableChannel, io:DEFAULT_ENCODING);
-    string[] lines = check readableCharChannel.readAllLines();
+    io:ReadableByteChannel byteChannel = check io:createReadableChannel(yamlString.toBytes());
+    io:ReadableCharacterChannel charChannel = new (byteChannel, io:DEFAULT_ENCODING);
+    string[] lines = check charChannel.readAllLines();
     return readLines(lines, config);
 }