14 files changed, 407 insertions, 65 deletions

diff --git a/Makefile b/Makefile
index e19c75e..399128b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,10 @@
-CFLAGS = -Wall -Wextra -g3 -ansi -pedantic
-OBJ = build/main.o build/tokenizer.o build/parser.o build/bytecode.o build/buffer.o
+CFLAGS = -Wall -Wextra -g3 -ansi -pedantic -fPIE
+LIBS = -Wl,-Bdynamic -lcurl
+OBJ = build/main.o build/tokenizer.o build/parser.o build/bytecode.o build/buffer.o build/hash_map.o
+CC = cc
 
 all: build_dir $(OBJ)
-	cc -o build/tsl $(OBJ) -fPIE
+	$(CC) -o build/tsl $(OBJ) $(LIBS)
 
 clean:
 	rm $(OBJ) build/tsl
@@ -14,16 +16,19 @@ compiledb:
 	make clean; bear make
 
 build/main.o: src/main.c include/tokenizer.h
-	cc -c src/main.c -o build/main.o $(CFLAGS)
+	$(CC) -c src/main.c -o build/main.o $(CFLAGS)
 
 build/tokenizer.o: src/tokenizer.c include/tokenizer.h
-	cc -c src/tokenizer.c -o build/tokenizer.o $(CFLAGS)
+	$(CC) -c src/tokenizer.c -o build/tokenizer.o $(CFLAGS)
 
 build/parser.o: src/parser.c include/parser.h
-	cc -c src/parser.c -o build/parser.o $(CFLAGS)
+	$(CC) -c src/parser.c -o build/parser.o $(CFLAGS)
 
 build/bytecode.o: src/bytecode.c include/bytecode.h
-	cc -c src/bytecode.c -o build/bytecode.o $(CFLAGS)
+	$(CC) -c src/bytecode.c -o build/bytecode.o $(CFLAGS)
 
 build/buffer.o: src/std/buffer.c include/std/buffer.h
-	cc -c src/std/buffer.c -o build/buffer.o $(CFLAGS)
+	$(CC) -c src/std/buffer.c -o build/buffer.o $(CFLAGS)
+
+build/hash_map.o: src/std/hash_map.c include/std/hash_map.h
+	$(CC) -c src/std/hash_map.c -o build/hash_map.o $(CFLAGS)
diff --git a/README.md b/README.md
index 7710e4b..c9c3a82 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,5 @@
 A tiny scripting language that is designed to be a replacement for small shell/python scripts.\
 Written in ANSI C to allow embedding everywhere and a WTFPL license that allows it to be used anywhere without any restrictions.
+# TODO
+* Remove dependency on `gc`. Write our own gc instead.
+* Implement big int, which numbers should automatically switch to when they are too large to fit into double.
\ No newline at end of file
diff --git a/example.tsl b/example.tsl
index cfb3f5a..b81af3d 100644
--- a/example.tsl
+++ b/example.tsl
@@ -16,4 +16,6 @@ value9 = {
 str = value9["hello"]
 value9["sayHello"]()
 
+value1 = value1 + 23
+
 response = $(curl https://example.com)
\ No newline at end of file
diff --git a/include/bytecode.h b/include/bytecode.h
index 4a14b8d..4a9d49c 100644
--- a/include/bytecode.h
+++ b/include/bytecode.h
@@ -4,37 +4,40 @@
 #include "std/buffer.h"
 #include <stdint.h>
 
-/*
-    All instructions are 4 bytes in size.
-*/
-
 typedef uint8_t TslOpcodeType;
-typedef uint8_t TslRegister;
+/* Registers are positive if they refer to local variables and negative when they refer to parameters */
+typedef int16_t TslRegister;
 typedef uint16_t TslValueIndex;
 
 typedef enum {
-    TSL_OPCODE_ASSIGN
+    TSL_OPCODE_LOAD_NUMBER,
+    TSL_OPCODE_MOV_REG
 } TslOpcode;
 
 typedef struct {
     TslBuffer buffer;
+    TslRegister register_counter;
 } TslBytecodeWriter;
 
 typedef struct {
+    TslRegister dst_reg;
+    double number;
+    TslOpcodeType opcode;
+} TslInstructionType1;
+
+typedef struct {
+    TslRegister dst_reg;
+    TslRegister src_reg;
     TslOpcodeType opcode;
-    union {
-        TslRegister dst_reg;
-        TslRegister src_reg;
-    } type1;
-    union {
-        TslRegister dst_reg;
-        TslValueIndex value_index;
-    } type2;
-} TslInstruction;
+} TslInstructionType2;
 
 void tsl_bytecode_writer_init(TslBytecodeWriter *self);
 void tsl_bytecode_writer_deinit(TslBytecodeWriter *self);
+void tsl_bytecode_writer_reset_register_counter(TslBytecodeWriter *self);
+/* Returns -1 on error (too many registers used (more than 2^15)) */
+TslRegister tsl_bytecode_writer_get_unique_register(TslBytecodeWriter *self);
 
-int tsl_bytecode_writer_assign(TslBytecodeWriter *self, TslRegister reg, double value);
+int tsl_bytecode_writer_load_number(TslBytecodeWriter *self, TslRegister dst, double number);
+int tsl_bytecode_writer_mov_reg(TslBytecodeWriter *self, TslRegister dst, TslRegister src);
 
 #endif /* TSL_BYTECODE_H */
diff --git a/include/std/buffer.h b/include/std/buffer.h
index dea7dbd..db6474e 100644
--- a/include/std/buffer.h
+++ b/include/std/buffer.h
@@ -16,6 +16,8 @@ typedef struct {
 void tsl_buffer_init(TslBuffer *self);
 void tsl_buffer_deinit(TslBuffer *self);
 
-int tsl_buffer_append(TslBuffer *self, void *data, size_t size);
+int tsl_buffer_append(TslBuffer *self, const void *data, size_t size);
+void* tsl_buffer_begin(TslBuffer *self);
+void* tsl_buffer_end(TslBuffer *self);
 
 #endif /* TSL_BUFFER_H */
diff --git a/include/std/hash_map.h b/include/std/hash_map.h
new file mode 100644
index 0000000..f3a3a6d
--- /dev/null
+++ b/include/std/hash_map.h
@@ -0,0 +1,24 @@
+#ifndef TSL_HASH_MAP_H
+#define TSL_HASH_MAP_H
+
+#include "string_view.h"
+#include <stdint.h>
+
+typedef uint64_t (*TslHashFunc)(const void *data, size_t size);
+
+/* TODO: Optimize small hash map by using the members of the struct instead of allocating on heap */
+typedef struct {
+    void *buckets_data; /* value=TslHashMapNode<void*>, data=|hash(uint64_t) + key_size(size_t) + key_data(...) data_size(size_t) + data_data(...)| */
+    size_t buckets_size;
+    size_t buckets_capacity;
+    size_t num_items;
+} TslHashMap;
+
+void tsl_hash_map_init(TslHashMap *self);
+void tsl_hash_map_deinit(TslHashMap *self);
+
+int tsl_hash_map_insert(TslHashMap *self, const TslStringView *key, const void *data, size_t size, TslHashFunc hash_func);
+/* Get a reference to the value by key @key */
+void* tsl_hash_map_get(TslHashMap *self, const TslStringView *key, TslHashFunc hash_func);
+
+#endif /* TSL_HASH_MAP_H */
diff --git a/include/std/string_view.h b/include/std/string_view.h
new file mode 100644
index 0000000..4f9552a
--- /dev/null
+++ b/include/std/string_view.h
@@ -0,0 +1,11 @@
+#ifndef TSL_STRING_VIEW_H
+#define TSL_STRING_VIEW_H
+
+#include <stddef.h>
+
+typedef struct {
+    const char *data;
+    size_t size;
+} TslStringView;
+
+#endif /* TSL_STRING_VIEW_H */
diff --git a/include/tokenizer.h b/include/tokenizer.h
index 98491c7..2e7d42b 100644
--- a/include/tokenizer.h
+++ b/include/tokenizer.h
@@ -1,13 +1,7 @@
 #ifndef TSL_TOKENIZER_H
 #define TSL_TOKENIZER_H
 
-#include <stddef.h>
-#include <stdint.h>
-
-typedef struct {
-    const char *data;
-    size_t size;
-} TslStringView;
+#include "std/string_view.h"
 
 typedef enum {
     TSL_TOKEN_END_OF_FILE,
@@ -27,7 +21,8 @@ typedef enum {
     TSL_TOKEN_COLON,
     TSL_TOKEN_COMMA,
     TSL_TOKEN_FN,
-    TSL_TOKEN_DOLLAR_SIGN
+    TSL_TOKEN_DOLLAR_SIGN,
+    TSL_TOKEN_ARITHMETIC
 } TslToken;
 
 typedef enum {
@@ -53,14 +48,20 @@ typedef struct {
     TslStringView identifier;
     TslStringView string;
     int bool_value;
-    int64_t number_value;
+    double number_value;
+    char arithmetic_symbol;
 } TslTokenizer;
 
 void tsl_tokenizer_init(TslTokenizer *self, const char *code, size_t code_size);
 
 TslToken tsl_tokenizer_next(TslTokenizer *self);
 int tsl_tokenizer_accept(TslTokenizer *self, TslToken expected_token);
+/*
+    If peek was previously called without consuming the token, then the previous value peek token is returned.
+    In other words, calling tsl_tokenizer_peek twice in a row will return the same token without progressing.
+*/
 TslToken tsl_tokenizer_peek(TslTokenizer *self);
+TslToken tsl_tokenizer_consume_peek(TslTokenizer *self);
 
 TslCommandToken tsl_tokenizer_next_command_arg(TslTokenizer *self, TslStringView *arg);
 
diff --git a/include/value.h b/include/value.h
new file mode 100644
index 0000000..1d053b7
--- /dev/null
+++ b/include/value.h
@@ -0,0 +1,49 @@
+#ifndef TSL_VALUE_H
+#define TSL_VALUE_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+typedef enum {
+    TSL_TYPE_NULL,
+    TSL_TYPE_NUMBER,
+    TSL_TYPE_STRING,
+    TSL_TYPE_BOOL,
+    TSL_TYPE_LIST,
+    TSL_TYPE_MAP,
+    TSL_TYPE_USERDATA
+} TslType;
+
+typedef enum {
+    TSL_FALSE,
+    TSL_TRUE
+} TslBool;
+
+typedef struct {
+    char *data;
+    size_t size;
+} TslString;
+
+/* TODO: Implement this */
+typedef struct {
+    void *data;
+} TslList;
+
+/* TODO: Implement this */
+typedef struct {
+    void *data;
+} TslMap;
+
+typedef struct {
+    union {
+        double number;
+        TslString *string;
+        TslBool boolean;
+        TslList *list;
+        TslMap *map;
+        void *userdata;
+    } data;
+    uint8_t type;
+} TslValue;
+
+#endif /* TSL_VALUE_H */
diff --git a/src/bytecode.c b/src/bytecode.c
index 3e9a6e8..a0b5406 100644
--- a/src/bytecode.c
+++ b/src/bytecode.c
@@ -2,18 +2,36 @@
 #include <assert.h>
 
 void tsl_bytecode_writer_init(TslBytecodeWriter *self) {
-    assert(sizeof(TslInstruction) == 4);
     tsl_buffer_init(&self->buffer);
+    self->register_counter = 0;
 }
 
 void tsl_bytecode_writer_deinit(TslBytecodeWriter *self) {
     tsl_buffer_deinit(&self->buffer);
 }
 
-int tsl_bytecode_writer_assign(TslBytecodeWriter *self, TslRegister reg, double value) {
-    TslInstruction instruction;
-    instruction.opcode = TSL_OPCODE_ASSIGN;
-    instruction.type2.dst_reg = reg;
-    instruction.type2.value_index = value;
+void tsl_bytecode_writer_reset_register_counter(TslBytecodeWriter *self) {
+    self->register_counter = 0;
+}
+
+TslRegister tsl_bytecode_writer_get_unique_register(TslBytecodeWriter *self) {
+    if(self->register_counter < INT16_MAX)
+        return self->register_counter++;
+    return -1;
+}
+
+int tsl_bytecode_writer_load_number(TslBytecodeWriter *self, TslRegister dst, double number) {
+    TslInstructionType1 instruction;
+    instruction.opcode = TSL_OPCODE_LOAD_NUMBER;
+    instruction.dst_reg = dst;
+    instruction.number = number;
+    return tsl_buffer_append(&self->buffer, &instruction, sizeof(instruction));
+}
+
+tsl_bytecode_writer_mov_reg(TslBytecodeWriter *self, TslRegister dst, TslRegister src) {
+    TslInstructionType2 instruction;
+    instruction.opcode = TSL_OPCODE_MOV_REG;
+    instruction.dst_reg = dst;
+    instruction.src_reg = src;
     return tsl_buffer_append(&self->buffer, &instruction, sizeof(instruction));
 }
diff --git a/src/parser.c b/src/parser.c
index 176be63..45b4412 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -150,7 +150,7 @@ static int tsl_parser_parse_func_call(TslParser *self) {
     for(;;) {
         TslToken token = tsl_tokenizer_peek(&self->tokenizer);
         if(token == TSL_TOKEN_RPAREN) {
-            tsl_tokenizer_next(&self->tokenizer); /* consume previous TSL_TOKEN_RPAREN */
+            tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_RPAREN */
             return 0;
         } else {
             if(tsl_parser_parse_rhs(self) != 0)
@@ -189,7 +189,7 @@ static int tsl_parser_parse_command(TslParser *self) {
     }
 }
 
-/* RHS_SUB = VAR_INDEX|FUNC_CALL RHS_SUB? */
+/* RHS_SUB = (VAR_INDEX|FUNC_CALL RHS_SUB?)|(TOKEN_ARITHMETIC RHS) */
 static int tsl_parser_parse_rhs_sub(TslParser *self) {
     TslToken token = tsl_tokenizer_peek(&self->tokenizer);
     if(token == TSL_TOKEN_LBRACKET) {
@@ -200,6 +200,27 @@ static int tsl_parser_parse_rhs_sub(TslParser *self) {
         if(tsl_parser_parse_func_call(self) != 0)
             return -1;
         return tsl_parser_parse_rhs_sub(self);
+    } else if(token == TSL_TOKEN_ARITHMETIC) {
+        tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_ARITHMETIC */
+        printf("rhs sub arithmetic symbol: %c\n", self->tokenizer.arithmetic_symbol);
+        /* TODO: Handle arithmetic expression precedence */
+        return tsl_parser_parse_rhs(self);
+    }
+    /*
+        No sub expression found, possibly a new expression after this (a new expression on a new line), let that
+        part of the code handle error if there is any instead.
+    */
+    return 0;
+}
+
+/* RHS_SUB_ARITHMETIC = TOKEN_ARITHMETIC RHS */
+static int tsl_parser_parse_rhs_sub_arithmetic(TslParser *self) {
+    TslToken token = tsl_tokenizer_peek(&self->tokenizer);
+    if(token == TSL_TOKEN_ARITHMETIC) {
+        tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_ARITHMETIC */
+        printf("rhs sub arithmetic symbol: %c\n", self->tokenizer.arithmetic_symbol);
+        /* TODO: Handle arithmetic expression precedence */
+        return tsl_parser_parse_rhs(self);
     }
     /*
         No sub expression found, possibly a new expression after this (a new expression on a new line), let that
@@ -213,10 +234,20 @@ int tsl_parser_parse_rhs(TslParser *self) {
     TslToken token = tsl_tokenizer_next(&self->tokenizer);
     if(token == TSL_TOKEN_IDENTIFIER) {
         TslStringView var_name = self->tokenizer.identifier;
-        printf("var: %.*s\n", (int)var_name.size, var_name.data);
+        printf("rhs var: %.*s\n", (int)var_name.size, var_name.data);
         return tsl_parser_parse_rhs_sub(self);
     } else if(token == TSL_TOKEN_NUM) {
-        printf("rhs num: %ld\n", self->tokenizer.number_value);
+        TslRegister dst_reg = tsl_bytecode_writer_get_unique_register(&self->bytecode_writer);
+        if(dst_reg == -1) {
+            fprintf(stderr, "Error: Too many registers used\n");
+            return -1;
+        }
+
+        if(!tsl_bytecode_writer_load_number(&self->bytecode_writer, dst_reg, self->tokenizer.number_value))
+            return -1;
+
+        printf("rhs num: %f\n", self->tokenizer.number_value);
+        return tsl_parser_parse_rhs_sub_arithmetic(self);
     } else if(token == TSL_TOKEN_BOOL) {
         printf("rhs bool: %s\n", self->tokenizer.bool_value ? "true" : "false");
     } else if(token == TSL_TOKEN_NULL) {
@@ -249,7 +280,7 @@ int tsl_parser_parse_expressions(TslParser *self, TslToken end_token) {
             TslStringView identifier = self->tokenizer.identifier;
             printf("identifier: %.*s\n", identifier.size, identifier.data);
             if(tsl_tokenizer_peek(&self->tokenizer) == TSL_TOKEN_EQUAL) {
-                tsl_tokenizer_next(&self->tokenizer); /* consume previous TSL_TOKEN_EQUAL */
+                tsl_tokenizer_consume_peek(&self->tokenizer); /* consume previous TSL_TOKEN_EQUAL */
                 if(tsl_parser_parse_rhs(self) != 0)
                     return -1;
             } else {
diff --git a/src/std/buffer.c b/src/std/buffer.c
index 3fc5184..42b1a0f 100644
--- a/src/std/buffer.c
+++ b/src/std/buffer.c
@@ -1,4 +1,5 @@
 #include "../../include/std/buffer.h"
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -25,18 +26,28 @@ static int tsl_buffer_ensure_capacity(TslBuffer *self, size_t new_size) {
         new_size = new_capacity;
     }
     new_ptr = realloc(self->data, new_size);
-    if(!new_ptr)
+    if(!new_ptr) {
+        fprintf(stderr, "Error: buffer append failed. Reason: out of memory\n");
         return 0;
+    }
 
     self->data = new_ptr;
     self->capacity = new_size;
     return 1;
 }
 
-int tsl_buffer_append(TslBuffer *self, void *data, size_t size) {
+int tsl_buffer_append(TslBuffer *self, const void *data, size_t size) {
     if(!tsl_buffer_ensure_capacity(self, self->size + size))
-        return 1;
+        return 0;
     memcpy((char*)self->data + self->size, data, size);
     self->size += size;
-    return 0;
+    return 1;
+}
+
+void* tsl_buffer_begin(TslBuffer *self) {
+    return self->data;
+}
+
+void* tsl_buffer_end(TslBuffer *self) {
+    return (char*)self->data + self->size;
 }
diff --git a/src/std/hash_map.c b/src/std/hash_map.c
new file mode 100644
index 0000000..a0d656d
--- /dev/null
+++ b/src/std/hash_map.c
@@ -0,0 +1,170 @@
+#include "../../include/std/hash_map.h"
+#include <assert.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+void tsl_hash_map_init(TslHashMap *self) {
+    self->buckets_data = NULL;
+    self->buckets_size = 0;
+    self->buckets_capacity = 0;
+    self->num_items = 0;
+}
+
+void tsl_hash_map_deinit(TslHashMap *self) {
+    free(self->buckets_data);
+}
+
+typedef struct TslHashMapNode TslHashMapNode;
+struct TslHashMapNode {
+    void *data;
+    TslHashMapNode *next;
+};
+
+static void hash_map_node_init(TslHashMapNode *self) {
+    self->data = NULL;
+    self->next = NULL;
+}
+
+static void hash_map_node_get(TslHashMapNode *self, uint64_t *hash, TslStringView *key, size_t *size, uint8_t **data) {
+    memcpy(hash, (uint8_t*)self->data, sizeof(uint64_t));
+    memcpy(&key->size, (uint8_t*)self->data + sizeof(uint64_t), sizeof(key->size));
+    key->data = (const char*)self->data + sizeof(uint64_t) + sizeof(key->size);
+    memcpy(size, (uint8_t*)self->data + sizeof(uint64_t) + sizeof(key->size) + key->size, sizeof(size_t));
+    *data = (uint8_t*)self->data + sizeof(uint64_t) + sizeof(key->size) + key->size + sizeof(size_t);
+}
+
+static int tsl_hash_map_append_bucket(TslHashMapNode **head_node, uint64_t hash, const TslStringView *key, size_t size, const void *data) {
+    TslHashMapNode *next_node;
+    uint8_t *node_data = malloc(sizeof(hash) + sizeof(size) + size);
+    if(!node_data) {
+        fprintf(stderr, "Error: hash map append failed. Reason: out of memory\n");
+        return 0;
+    }
+
+    next_node = malloc(sizeof(TslHashMapNode));
+    if(!next_node) {
+        free(node_data);
+        fprintf(stderr, "Error: hash map append failed. Reason: out of memory\n");
+        return 0;
+    }
+    hash_map_node_init(next_node);
+
+    memcpy(node_data, &hash, sizeof(hash));
+    memcpy(node_data + sizeof(hash), &key->size, sizeof(key->size));
+    memcpy(node_data + sizeof(hash) + sizeof(key->size), key->data, key->size);
+    memcpy(node_data + sizeof(hash) + sizeof(key->size) + key->size, &size, sizeof(size));
+    memcpy(node_data + sizeof(hash) + sizeof(key->size) + key->size + sizeof(size), data, size);
+
+    if(*head_node) {
+        (*head_node)->data = node_data;
+        (*head_node)->next = next_node;
+    }
+    *head_node = next_node;
+    return 1;
+}
+
+static int tsl_hash_map_ensure_bucket_capacity(TslHashMap *self, size_t new_size) {
+    size_t new_capacity = self->num_items;
+    void *new_ptr;
+    if(new_size <= self->num_items)
+        return 1;
+
+    if(new_capacity == 0)
+        new_capacity = 8;
+
+    while(new_capacity < new_size) {
+        new_capacity *= 2;
+    }
+
+    new_ptr = realloc(self->buckets_data, new_capacity);
+    if(!new_ptr) {
+        fprintf(stderr, "Error: hash map realloc failed. Reason: out of memory\n");
+        return 0;
+    }
+
+    self->buckets_data = new_ptr;
+    self->buckets_capacity = new_capacity;
+    {
+        TslHashMapNode **bucket = (TslHashMapNode**)((char*)self->buckets_data + self->buckets_size);
+        TslHashMapNode **bucket_end = (TslHashMapNode**)((char*)self->buckets_data + self->buckets_capacity);
+        while(bucket != bucket_end) {
+            *bucket = NULL;
+            ++bucket;
+        }
+    }
+
+    {
+        TslHashMapNode **bucket = (TslHashMapNode**)self->buckets_data;
+        TslHashMapNode **bucket_end = (TslHashMapNode**)((char*)self->buckets_data + self->buckets_capacity);
+        size_t bucket_index = 0;
+        while(bucket != bucket_end) {
+            TslHashMapNode *node = *bucket;
+            TslHashMapNode *prev_node = node; /* Set to node for optimization reason, where prev_node->next = node->next; which becomes no-op */
+            while(node) {
+                uint64_t hash;
+                TslStringView key;
+                size_t size;
+                uint8_t *data;
+                size_t index;
+                hash_map_node_get(node, &hash, &key, &size, &data);
+
+                index = hash & (self->buckets_capacity - 1);
+                if(index != bucket_index) {
+                    TslHashMapNode **new_bucket = (TslHashMapNode**)self->buckets_data + index;
+                    prev_node->next = node->next;
+                    if(*new_bucket) {
+                        node->next = (*new_bucket)->next;
+                        (*new_bucket)->next = node;
+                    } else {
+                        node->next = NULL;
+                        *new_bucket = node;
+                    }
+                }
+
+                prev_node = node;
+                node = node->next;
+            }
+            ++bucket_index;
+            ++bucket;
+        }
+    }
+    return 1;
+}
+
+int tsl_hash_map_insert(TslHashMap *self, const TslStringView *key, const void *data, size_t size, TslHashFunc hash_func) {
+    uint64_t hash = hash_func(key->data, key->size);
+    size_t index;
+    TslHashMapNode **bucket;
+    assert(!tsl_hash_map_get(self, key, hash_func));
+    if(!tsl_hash_map_ensure_bucket_capacity(self, self->buckets_size + size))
+        return 0;
+
+    index = hash & (self->buckets_capacity - 1);
+    bucket = (TslHashMapNode**)self->buckets_data + index;
+    return tsl_hash_map_append_bucket(bucket, hash, key, size, data);
+}
+
+void* tsl_hash_map_get(TslHashMap *self, const TslStringView *key, TslHashFunc hash_func) {
+    uint64_t hash;
+    size_t index;
+    TslHashMapNode *node;
+    if(self->buckets_capacity == 0)
+        return NULL;
+
+    hash = hash_func(key->data, key->size);
+    index = hash & (self->buckets_capacity - 1);
+    node = *((TslHashMapNode**)self->buckets_data + index);
+    while(node) {
+        uint64_t node_hash;
+        TslStringView node_key;
+        size_t node_size;
+        uint8_t *node_data;
+        hash_map_node_get(node, &node_hash, &node_key, &node_size, &node_data);
+        if(hash == node_hash && key->size == node_key.size && memcmp(key->data, node_key.data, node_key.size) == 0)
+            return node_data;
+        node = node->next;
+    }
+
+    return NULL;
+}
diff --git a/src/tokenizer.c b/src/tokenizer.c
index 89c40cb..889152b 100644
--- a/src/tokenizer.c
+++ b/src/tokenizer.c
@@ -2,6 +2,7 @@
 #include <string.h>
 #include <stdio.h>
 #include <assert.h>
+#include <stdint.h>
 
 void tsl_tokenizer_init(TslTokenizer *self, const char *code, size_t code_size) {
     self->code = code;
@@ -19,6 +20,7 @@ void tsl_tokenizer_init(TslTokenizer *self, const char *code, size_t code_size)
     self->string.size = 0;
     self->bool_value = 0;
     self->number_value = 0;
+    self->arithmetic_symbol = '\0';
 }
 
 static char tsl_tokenizer_get_char(TslTokenizer *self) {
@@ -173,6 +175,7 @@ static TslToken tsl_tokenizer_next_internal(TslTokenizer *self) {
         }
         self->identifier.data = self->code + num_start;
         self->identifier.size = self->code_index - num_start;
+        /* TODO: Check if the result of string_to_int is too large to fit into double */
         self->number_value = string_to_int(&self->identifier);
         return TSL_TOKEN_NUM;
     } else if(c == '"') {
@@ -217,6 +220,10 @@ static TslToken tsl_tokenizer_next_internal(TslTokenizer *self) {
     } else if(c == '$') {
         ++self->code_index;
         return TSL_TOKEN_DOLLAR_SIGN;
+    } else if(c == '+' || c == '-' || c == '*' || c == '/') {
+        self->arithmetic_symbol = c;
+        ++self->code_index;
+        return TSL_TOKEN_ARITHMETIC;
     } else if(c == '\0') {
         return TSL_TOKEN_END_OF_FILE;
     } else {
@@ -225,14 +232,6 @@ static TslToken tsl_tokenizer_next_internal(TslTokenizer *self) {
     }
 }
 
-static TslToken tsl_tokenizer_consume_peek(TslTokenizer *self) {
-    TslToken token = self->peek.token;
-    self->code_index = self->peek.code_index;
-    self->prev_code_index = self->peek.prev_code_index;
-    self->peek.token = -1;
-    return token;
-}
-
 TslToken tsl_tokenizer_next(TslTokenizer *self) {
     if((int)self->peek.token == -1) {
         return tsl_tokenizer_next_internal(self);
@@ -256,16 +255,29 @@ int tsl_tokenizer_accept(TslTokenizer *self, TslToken expected_token) {
 }
 
 TslToken tsl_tokenizer_peek(TslTokenizer *self) {
-    size_t p_prev_code_index = self->prev_code_index;
-    size_t p_code_index = self->code_index;
+    if((int)self->peek.token == -1) {
+        size_t p_prev_code_index = self->prev_code_index;
+        size_t p_code_index = self->code_index;
 
-    self->peek.token = tsl_tokenizer_next_internal(self);
-    self->peek.code_index = self->code_index;
-    self->peek.prev_code_index = self->prev_code_index;
+        self->peek.token = tsl_tokenizer_next_internal(self);
+        self->peek.code_index = self->code_index;
+        self->peek.prev_code_index = self->prev_code_index;
 
-    self->prev_code_index = p_prev_code_index;
-    self->code_index = p_code_index;
-    return self->peek.token;
+        self->prev_code_index = p_prev_code_index;
+        self->code_index = p_code_index;
+        return self->peek.token;
+    } else {
+        return self->peek.token;
+    }
+}
+
+TslToken tsl_tokenizer_consume_peek(TslTokenizer *self) {
+    TslToken token = self->peek.token;
+    assert((int)token != -1);
+    self->code_index = self->peek.code_index;
+    self->prev_code_index = self->peek.prev_code_index;
+    self->peek.token = -1;
+    return token;
 }
 
 TslCommandToken tsl_tokenizer_next_command_arg(TslTokenizer *self, TslStringView *arg) {