Implemented 'Toy_Table' hashtable with robin hood algorithm, untested

source/toy_table.c

@@ -0,0 +1,162 @@
+#include "toy_table.h"
+#include "toy_console_colors.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+//'count' actually tracks the number of values
+#define MIN_CAPACITY 16
+
+//utils
+static Toy_Table* adjustTableCapacity(Toy_Table* oldTable, unsigned int newCapacity) {
+	//allocate and zero a new table in memory
+	Toy_Table* newTable = malloc(newCapacity * sizeof(Toy_TableEntry) + sizeof(Toy_Table));
+
+	newTable->capacity = newCapacity;
+	newTable->count = 0;
+	newTable->minPsl = 0;
+	newTable->maxPsl = 0;
+
+	//unlike other structures, the empty space in a table needs to be null
+	memset(newTable + 1, 0, newTable->capacity * sizeof(Toy_TableEntry));
+
+	if (oldTable == NULL) { //for initial allocations
+		return newTable;
+	}
+
+	//for each entry in the old table, copy it into the new table
+	for (int i = 0; i < oldTable->capacity; i++) {
+		Toy_insertTable(&newTable, oldTable->data[i].key, oldTable->data[i].value);
+	}
+
+	//clean up and return
+	free(oldTable);
+	return newTable;
+}
+
+//exposed functions
+Toy_Table* Toy_allocateTable() {
+	return adjustTableCapacity(NULL, MIN_CAPACITY);
+}
+
+void Toy_freeTable(Toy_Table* table) {
+	//TODO: slip in a call to free the complex values here
+
+	free(table);
+}
+
+void Toy_insertTable(Toy_Table** table, Toy_Value key, Toy_Value value) {
+	if (TOY_VALUE_IS_NULL(key) || TOY_VALUE_IS_BOOLEAN(key)) { //TODO: disallow functions and opaques
+		fprintf(stderr, TOY_CC_ERROR "ERROR: Bad table key\n" TOY_CC_RESET);
+		exit(-1); //TODO: #127
+	}
+
+	//expand the capacity
+	if ((*table)->capacity < (*table)->count * (1 / 0.75f)) {
+		(*table) = adjustTableCapacity(*table, (*table)->capacity * 2);
+	}
+
+	//insert
+	unsigned int probe = Toy_hashValue(key) % (*table)->capacity;
+	Toy_TableEntry entry = (Toy_TableEntry){ .key = key, .value = value, .psl = 0 };
+
+	while (true) {
+		//if this spot is free, insert and return
+		if (TOY_VALUE_IS_NULL((*table)->data[probe].key)) {
+			(*table)->data[probe] = entry;
+
+			(*table)->count++;
+
+			//TODO: benchmark the psl optimisation
+			(*table)->minPsl = entry.psl < (*table)->minPsl ? entry.psl : (*table)->minPsl;
+			(*table)->maxPsl = entry.psl > (*table)->maxPsl ? entry.psl : (*table)->maxPsl;
+
+			return;
+		}
+
+		//if the new entry is "poorer", insert it and shift the old one
+		if ((*table)->data[probe].psl < entry.psl) {
+			Toy_TableEntry tmp = (*table)->data[probe];
+			(*table)->data[probe] = entry;
+			entry = tmp;
+		}
+
+		//adjust and continue
+		probe = (probe + 1) % (*table)->capacity;
+		entry.psl++;
+	}
+}
+
+Toy_Value Toy_lookupTableValue(Toy_Table** table, Toy_Value key) {
+	if (TOY_VALUE_IS_NULL(key) || TOY_VALUE_IS_BOOLEAN(key)) { //TODO: disallow functions and opaques
+		fprintf(stderr, TOY_CC_ERROR "ERROR: Bad table key\n" TOY_CC_RESET);
+		exit(-1); //TODO: #127
+	}
+
+	//lookup
+	unsigned int probe = Toy_hashValue(key) % (*table)->capacity;
+	unsigned int counter = 0;
+
+	while (true) {
+		//found the entry
+		if (TOY_VALUE_IS_EQUAL((*table)->data[probe].key, key)) {
+			return (*table)->data[probe].value;
+		}
+
+		//if the psl is too big, or empty slot
+		if ((*table)->data[probe].psl > counter || TOY_VALUE_IS_NULL((*table)->data[probe].key)) {
+			return TOY_VALUE_TO_NULL();
+		}
+
+		//adjust and continue
+		probe = (probe + 1) % (*table)->capacity;
+		counter++;
+	}
+}
+
+void Toy_removeTableEntry(Toy_Table** table, Toy_Value key) {
+	if (TOY_VALUE_IS_NULL(key) || TOY_VALUE_IS_BOOLEAN(key)) { //TODO: disallow functions and opaques
+		fprintf(stderr, TOY_CC_ERROR "ERROR: Bad table key\n" TOY_CC_RESET);
+		exit(-1); //TODO: #127
+	}
+
+	//lookup
+	unsigned int probe = Toy_hashValue(key) % (*table)->capacity;
+	unsigned int counter = 0;
+	unsigned int wipe = probe; //wiped at the end
+
+	while (true) {
+		//found the entry
+		if (TOY_VALUE_IS_EQUAL((*table)->data[probe].key, key)) {
+			break;
+		}
+
+		//if the psl is too big, or empty slot
+		if ((*table)->data[probe].psl > counter || TOY_VALUE_IS_NULL((*table)->data[probe].key)) {
+			return;
+		}
+
+		//adjust and continue
+		probe = (probe + 1) % (*table)->capacity;
+		counter++;
+	}
+
+	//shift down the later entries (past the probing point)
+	for (unsigned int i = (*table)->minPsl; i < (*table)->maxPsl; i++) {
+		unsigned int p = (probe + i + 0) % (*table)->capacity; //prev
+		unsigned int u = (probe + i + 1) % (*table)->capacity; //current
+
+		//if the psl is too big, or an empty slot, stop
+		if ((*table)->data[u].psl > (counter + i) || TOY_VALUE_IS_NULL((*table)->data[u].key)) {
+			break;
+		}
+
+		(*table)->data[p] = (*table)->data[u];
+		(*table)->data[p].psl--;
+		wipe = wipe % (*table)->capacity;
+	}
+
+	//finally, wipe the removed entry
+	(*table)->data[wipe] = (Toy_TableEntry){ .key = TOY_VALUE_TO_NULL(), .value = TOY_VALUE_TO_NULL(), .psl = 0 };
+}