pebblisp/src/env.c

#include "env.h"
#include "pebblisp.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#ifndef STANDALONE
#include <pebble.h>
#undef printf
#define printf(...) APP_LOG(APP_LOG_LEVEL_DEBUG, __VA_ARGS__)
#endif

Object fetchFromEnvironment(const char *name, struct Environment *env)
{
    if(!env)
        return errorObject(NULL_ENV);

    if(env->size == 0)
        return errorObject(EMPTY_ENV);

    for(int i = 0; i < env->size; i++) {
        if(env->strings[i] == NULL) {
            printd("Try %d (NULL)\n", i);
            break;
        }

        printd("Try %d (%s)\n", i, env->strings[i]);
        debugObj(&env->objects[i]);
        if(strcmp(name, env->strings[i]) == 0) {
            printd("Returning!\n");
            return cloneObject(env->objects[i]);
        }
    }

    printd("Trying outer %p\n", env->outer);
    if(env->outer) {
        return fetchFromEnvironment(name, env->outer);
    }

    return errorObject(DID_NOT_FIND_SYMBOL);
}

struct Environment envForLambda(const Object *params, const Object *arg_forms,
                                struct Environment *outer)
{
    int paramCount = listLength(params);

    struct Environment env = {
        .outer = outer,
        .strings = NULL,
        .objects = NULL,
        .size = paramCount
    };

    if(paramCount == 0)
        return env;

    env.strings = calloc(sizeof(char*), paramCount + 1);
    env.objects = malloc(sizeof(Object) * (paramCount + 1));

    const Object *march = arg_forms;
    for(int i = 0; i < paramCount; i++) {
        const char *newObjName = itemAt(params, i)->string;
        // Eval the `march` list
        Object newEnvObj = eval(march, outer);
        addToEnv(&env, newObjName, newEnvObj); // Could use eval_forms?
        cleanObject(&newEnvObj);
        march = march->forward;
    }

    return env;
}

// Determine if a given symbol exists in the given environment chain
//
// Modifies `env` to the environment that the symbol was found in, only if the
// symbol was found
//
// Returns the index of the symbol in the environment, if found. Otherwise, -1
int findInEnv(struct Environment **env, const char *name)
{
    struct Environment *temp_env = *env;
    while(temp_env) {
        for(int i = 0; i < temp_env->size; i++) {
            if(temp_env->strings[i] == NULL) {
                break;
            }
            if(strcmp(temp_env->strings[i], name) == 0) {
                *env = temp_env;
                return i;
            }
        }
        temp_env = temp_env->outer;
    }
    return -1;
}

// TODO Maybe extend environment using a new outer, instead of realloc
void addToEnv(struct Environment *env, const char *name, const Object obj)
{
    // int sym_pos = findInEnv(&env, name);
    // if(sym_pos != -1) {
    //     Object o = cloneObject(obj);
    //     cleanObject(&env->objects[sym_pos]);
    //     env->objects[sym_pos] = o;
    //     return;
    // }

    int i;
    struct Environment *temp_env = env;
    int is_local = 1;
    while(temp_env) {
        for(i = 0; i < temp_env->size; i++) {
            // Add *new* item to env only if we're in the local scope
            if(temp_env->strings[i] == NULL) {
                if (is_local) {
                    temp_env->strings[i] = calloc(sizeof(char), strlen(name) + 1);
                    strncpy(temp_env->strings[i], name, strlen(name));
                    temp_env->objects[i] = cloneObject(obj);
                    return;
                }
                break;
            } else if(strcmp(temp_env->strings[i], name) == 0) {
                Object o = cloneObject(obj);
                cleanObject(&temp_env->objects[i]);
                temp_env->objects[i] = o;
                return;
            }
        }
        temp_env = temp_env->outer;
        is_local = 0;
    }

    printd("Reallocating environment\n");
    const int inc = 5;
    const int old_size = env->size;
    env->size += inc;
    env->strings = realloc(env->strings, sizeof(char*) * env->size);
    env->objects = realloc(env->objects, sizeof(Object) * env->size);

    for(int j = 0; j < inc; j++) {
        env->strings[old_size + j] = NULL;
    }

    env->strings[old_size] = malloc(strlen(name) + 1);
    strncpy(env->strings[old_size], name, strlen(name) + 1);
    env->objects[old_size] = cloneObject(obj);
}

void printEnv(struct Environment *env)
{
    if(!env) {
        printf("NULL env\n");
        return;
    }
    for(int i = 0; i < env->size; i++) {
        if(env->strings[i] == NULL) {
            printf("env[%d]: NULL %p\n", i, env->strings[i]);
            break;
        }
        printf("env[%d]: '%s' %p\n", i, env->strings[i], env->strings[i]);
        printf("  ");
        printObj(&env->objects[i]);
        printf("");
    }
}

void addFunc(const char *name, Object (*func)(Object, Object, struct Environment*),
             struct Environment *env)
{
    Object o = newObject(TYPE_FUNC);
    o.func = func;
    addToEnv(env, name, o);
}

void deleteEnv(struct Environment *e)
{
    int i = 0;
    while(e->strings[i]) {
        free(e->strings[i]);
        cleanObject(&e->objects[i]);
        i++;
    }
    free(e->strings);
    e->strings = NULL;

    free(e->objects);
    e->objects = NULL;
}

struct symFunc {
    const char *sym;
    Object (*func)(Object, Object, struct Environment*);
};

struct Environment defaultEnv()
{
    struct Environment e = {
        .outer = NULL,
        .strings = calloc(sizeof(char*), MAX_ENV_ELM),
        .objects = malloc(sizeof(Object) * MAX_ENV_ELM),
        .size = MAX_ENV_ELM
    };

    struct symFunc symFuncs[] = {
        {"+", &add}, {"-", &sub}, {"*", &mul}, {"/", &dvi}, {"%", &mod},
        {"=", &equ}, {">", &gth}, {"<", &lth},
        {"cat", &catObjects}, {"fil", &filter}, {"len", &len},
        {"ap", &append}, {"pre", &prepend},
        {"at", &at}, {"rest", &rest}, {"rev", &reverse},
        {"isnum", &isNum}, {"isstr", &isString}, {"iserr", &isErr},
        {"prn", &print}, {"pch", &pChar}, {"penv", &printEnvO},
        {"eval", &parseEvalO},
        #ifdef STANDALONE
        {"loadfile", &loadFile},
        {"inp", &takeInput},
        #endif
    };

    for(unsigned i = 0; i < sizeof(symFuncs)/sizeof(symFuncs[0]); i++) {
        addFunc(symFuncs[i].sym, symFuncs[i].func, &e);
    }

    return e;
}