c-scripting/examples/hooks.c

/*
** C Scripting - Hooks
*/

#define SY__MAIN 1
#include "symbol_set.h"
#include "symbol_set.init.h"

#include "hooks.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

////////////////////////////////
// Little Base Layer

static Arena
arena_alloc(U64 cap){
  Arena arena = {0};
  arena.memory = malloc(cap);
  arena.cap = cap;
  return(arena);
}

static void*
arena_push(Arena *arena, U64 size){
  void *result = 0;
  if (arena->pos + size <= arena->cap){
    result = (U8*)arena->memory + arena->pos;
    arena->pos += size;
    arena->pos = (arena->pos + 7)&~7; // "round up to multiple of 8"
    memset(result, 0, size);
  }
  return(result);
}

static void
arena_pop_to(Arena *arena, U64 pos){
  if (pos < arena->pos){
    arena->pos = (pos + 7)&~7; // "round up to multiple of 8"
  }
}

static U64
arena_pos(Arena *arena){
  return(arena->pos);
}

static void*
copy_strided(void *dst, U32 dst_stride,
             void *src, U32 src_stride,
             U32 count){
  void *base_src = src;
  void *base_dst = dst;
  if (dst_stride != src_stride){
    U32 size = Min(dst_stride, src_stride);
    for (U32 i = 0; i < count; i += 1){
      memcpy(dst, src, size);
      dst = (U8*)dst + dst_stride;
      src = (U8*)src + src_stride;
    }
  }
  else{
    memcpy(dst, src, dst_stride*count);
  }
  return(base_dst);
}

static void*
arena_push_symbol_set__raw(Arena *arena,
                           U32 size, void *src, U32 src_stride, U32 count){
  void *dst = push_array(arena, U8, size*(count + 1));
  copy_strided((U8*)dst + size, size, src, src_stride, count);
  return(dst);
}

////////////////////////////////
// Pretend "Core API"

typedef struct BufferRenderCtx{
  U32 dummy;
} BufferRenderCtx;

static void
color_range(Ctx *ctx, U32 min, U32 max){
  printf("DEMO: color_word(%p, %u, %u)\n", ctx, min, max);
}

////////////////////////////////
// Hooks

//// Symbols ////

HOOK_POINT_TYPE_DEF(BeginFrame, void);
HOOK_POINT_TYPE_DEF(EndFrame, void);

HOOK_POINT_STRUCT(RenderBuffer){
  U32 buffer_id;
};

PROCESS_TYPE(SearchWord);

PROCESS_HOOK(SearchWord, RenderBuffer){
  // imagine you get the string from the process
  String8 string = str8_const("c-scripting");
  
  // imagine you get the match ranges from searching params->buffer_id
  U32 range_count = 0;
  U32 rmin[3] = {0};
  if (params->buffer_id == 1){
    range_count = 3;
    memcpy(rmin, (U32[3]){ 1, 20, 152 }, 12);
  }
  else if (params->buffer_id == 2){
    range_count = 2;
    memcpy(rmin, (U32[2]){ 72, 510 }, 8);
  }
  
  // color the ranges
  for (U32 i = 0; i < range_count; i += 1){
    color_range(ctx, rmin[i], rmin[i] + string.size);
  }
}

//// Rules ////

static Rules
rules_from_symbol_sets(Arena *arena){
  // copy named symbol sets
  U32 hook_point_count = SyCount(HOOK_POINT) + 1;
  HookPoint *hook_points = arena_push_symbol_set(arena, HOOK_POINT);
  
  U32 process_type_count = SyCount(PROCESS_TYPE) + 1;
  ProcessType *process_types = arena_push_symbol_set(arena, PROCESS_TYPE);
  
  // process unnamed symbol sets
  HookFunc **func__process_hook =
    push_array(arena, HookFunc*, hook_point_count*process_type_count);
  for (SyEach(PROCESS_HOOK, link)){
    U32 idx = link->process_type_id*hook_point_count + link->hook_point_id;
    func__process_hook[idx] = link->func;
  }
  
  // rules
  Rules rules = {
    .hook_point_count = hook_point_count,
    .process_type_count = process_type_count,
    .hook_points = hook_points,
    .process_types = process_types,
    .func__process_hook = func__process_hook
  };
  return(rules);
}

static HookFunc*
rules_func_from_process_hook(Rules *rules, U32 process_type_id, U32 hook_point_id){
  U32 idx = process_type_id*rules->hook_point_count + hook_point_id;
  HookFunc *result = rules->func__process_hook[idx];
  return(result);
}

//// Context Functions ////

static void
ctx_new_process(Ctx *ctx, U32 process_type_id){
  if (ctx->process_count < sizeof(ctx->process_type_id)/sizeof(*ctx->process_type_id)){
    ctx->process_type_id[ctx->process_count] = process_type_id;
    ctx->process_count += 1;
  }
}

static void
ctx_hook_all_processes(Ctx *ctx, U32 hookp_id, void *params){
  for (U32 i = 0; i < ctx->process_count; i += 1){
    U32 process_type_id = ctx->process_type_id[i];
    HookFunc *func = rules_func_from_process_hook(ctx->rules, process_type_id, hookp_id);
    if (func != 0){
      func(ctx, params);
    }
  }
}

//// Entry Point ////

int main(void){
  sy__run_init();
  
  Arena arena = arena_alloc((10 << 20));
  
  Rules rules = rules_from_symbol_sets(&arena);
  
  Ctx ctx = {0};
  ctx.rules = &rules;
  ctx_new_process(&ctx, SyID(PROCESS_TYPE, SearchWord));
  
  for (U32 i = 0; i < 100; i += 1){
    ctx_hook_all_processes(&ctx, SyID(HOOK_POINT, BeginFrame), 0);
    
    for (U32 viewi = 0; viewi < 2; viewi += 1){
      // imagine each view has an assigned buffer
      U32 buffer_id = viewi + 1;
      
      // render the buffer
      HOOK_POINT_TYPE(RenderBuffer) params = {
        params.buffer_id = buffer_id
      };
      ctx_hook_all_processes(&ctx, SyID(HOOK_POINT, RenderBuffer), &params);
    }
    
    ctx_hook_all_processes(&ctx, SyID(HOOK_POINT, EndFrame), 0);
  }
  
  return(0);
}