Began basic syntax checking

1 files changed, 60 insertions, 8 deletions

diff --git a/src/runMain/kotlin/Syntax.kt b/src/runMain/kotlin/Syntax.kt
index 16304cc..a950e77 100644
--- a/src/runMain/kotlin/Syntax.kt
+++ b/src/runMain/kotlin/Syntax.kt
@@ -1,26 +1,47 @@
+import TokenType.*
+import exceptions.*
+
 class Syntax {
     /**
      * Checks and validates whether the code complies with the syntax/grammar rules
      */
     fun check(statements: MutableList<MutableList<Pair<String, TokenType>>>): Boolean {
-        statements.forEachIndexed { i, statement ->
+        statements.forEach { statement ->
             removePadding(statement)
             mergeStrings(statement)
+            mergeTokens(statement)
+            print(statement)
+            statement.forEachIndexed { j, token ->
+                when (token.second) {
+                    Keyword -> allowNext(statement, j, listOf(Assignment, Constant))
+                    Constant -> allowNext(statement, j, listOf(Comparison, Arithmetic, Logical, Bracket))
+                    Assignment -> allowNext(statement, j, listOf(Constant))
+                    Arithmetic -> allowNext(statement, j, listOf(Constant))
+                    Comparison -> allowNext(statement, j, listOf(Constant))
+                    Logical -> allowNext(statement, j, listOf(Constant))
+                    Identifier -> allowNext(statement, j, listOf(Keyword, Assignment))
+                    Punctuation -> allowNext(statement, j, listOf(Constant))
+                    Bracket -> allowNext(statement, j, listOf(Constant, Keyword, Logical, Assignment))
+                    Classifier -> {
+                    }
+                    Empty -> {
+                    }
+                    else -> throw UnknownType(token.first)
+                }
+            }
         }
         return true
     }
 
     /**
-     * Removed empty characters from the start and end of statements
+     * Removes empty characters from the start and end of statements
      */
     private fun removePadding(statement: MutableList<Pair<String, TokenType>>) {
-        while (statement[0].second == TokenType.Empty) {
+        while (statement[0].second == Empty)
             statement.removeAt(0)
-        }
 
-        while (statement[statement.size - 1].second == TokenType.Empty) {
+        while (statement[statement.size - 1].second == Empty)
             statement.removeAt(statement.size - 1)
-        }
     }
 
     /**
@@ -29,9 +50,40 @@ class Syntax {
     private fun mergeStrings(statement: MutableList<Pair<String, TokenType>>) {
         var stringing = false
         statement.forEachIndexed { i, token ->
-            if (token.second == TokenType.Classifier)
+            if (token.second == Classifier)
                 stringing = !stringing
-            if (stringing) statement[i] = token.first to TokenType.Constant
+            if (stringing || token.second == Classifier) statement[i] = token.first to Constant
+        }
+    }
+
+    /**
+     * Merges tokens by same type
+     */
+    private fun mergeTokens(statement: MutableList<Pair<String, TokenType>>) {
+        statement.forEachIndexed { i, token ->
+            if (statement.size > i + 1 && statement[i + 1].second == token.second) {
+                statement[i] = statement[i].first + statement[i + 1].first to token.second
+                statement.removeAt(i + 1)
+            }
         }
     }
+
+    /**
+     * Throws [SyntaxError] if the next token is not in [allowed]
+     */
+    private fun allowNext(statement: MutableList<Pair<String, TokenType>>, index: Int, allowed: List<TokenType>) {
+        if (nextNonEmpty(statement, index).second !in allowed) {
+            throw SyntaxError(nextNonEmpty(statement, index).first)
+        }
+    }
+
+    /**
+     * Finds the next non empty token by [index]
+     */
+    private fun nextNonEmpty(statement: MutableList<Pair<String, TokenType>>, index: Int): Pair<String, TokenType> {
+        var i = index + 1
+        while (statement[i].second == Empty)
+            i++
+        return statement[i]
+    }
 }
\ No newline at end of file