Add hooks and C structs

README.md

@@ -0,0 +1 @@
+

c.lua

@@ -0,0 +1,30 @@
+local c = {}
+
+function c.struct(name, fields_init)
+    local fields = fields_init or {}
+    local struct = {}
+    output:expression(function()
+        local s = "struct " .. name .. " {\n"
+        for _,v in pairs(fields) do
+            s = s .. "\t" .. v .. ";\n"
+        end
+        return s.. "};\n"
+    end)
+    setmetatable(struct, {
+        __index = fields,
+        __newindex = function(self, key, value)
+            if self[key] and self[key] ~= value then
+                error("Conflicting defintions of " .. name .. "." .. key .. ":\n\t'" .. self[key] .. "'\n\t'" .. value .. "'");
+            else
+                fields[key] = value
+            end
+        end,
+        __tostring = function()
+            return "struct " .. name
+        end
+    })
+    _G[name] = struct
+    return struct
+end
+
+return c

examples/linkedlist.c.mpp

@@ -0,0 +1,49 @@
+#include <stdlib.h>
+
+@function linkedlist(T, plugins)
+    @local l = mpp.c.struct("linkedlist_" .. T)
+    @local hooks = mpp.hooks()
+    @l.value = T.." value"
+    @l.next = tostring(l) .. " *next"
+
+    $T$ *ll_$T$_index(struct linkedlist_$T$ *list, size_t index) {
+        while(index > 0) {
+            if(!list->next) {
+                return NULL;
+            } else {
+                list = list->next;
+            }
+        }
+        return &list->value;
+    }
+
+    struct linkedlist_$T$ ll_$T$_cons($T$ value, struct linkedlist_$T$ *tail) {
+        struct linkedlist_$T$ l;
+        l.value = value;
+        l.next = tail;
+        @hooks("cons")
+        return l;
+    }
+    @for _,plugin in ipairs(plugins or {}) do plugin(T, l, hooks) end
+@end
+
+@function linkedlist_len_naive(T, l, hooks)
+    size_t ll_$T$_len(struct linkedlist_$T$ *list) {
+        size_t len = 0;
+        for(; list; len++) {
+            list = list->next;
+        }
+        return len;
+    }
+@end
+
+@function linkedlist_len_cached(T, l, hooks)
+    @l.size = "size_t size"
+    @hooks.cons("l.size = tail ? tail->size + 1 : 1;")
+    size_t ll_$T$_len(struct linkedlist_$T$ *list) {
+        return list->size;
+    }
+@end
+
+@linkedlist("int", {linkedlist_len_naive})
+@linkedlist("float", {linkedlist_len_cached})

examples/template.c.mpp

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <string.h>
+
+@mpp.c.struct("stats")
+@function counter(name) stats[name] = "size_t " .. name end
+struct stats stats;
+
+@function sum_t(type, base)
+    @local base = base or 0
+    $type$ sum_$type$($type$ *xs, size_t len) {
+        $type$ sum = $base$;
+        for(size_t i = 0; i < len; i++) {
+            @counter("summed" .. type)
+            stats.summed$type$++;
+            sum += xs[i];
+        }
+        return sum;
+    }
+@end
+
+@sum_t("int")
+@sum_t("float")
+
+int main() {
+    int xs[3] = {1, strlen("foo"), strlen("bar")};
+    int x = sum_int(xs, 3);
+    float ys[3] = {1.0, 3.14, 9.81};
+    float y = sum_float(ys, 3);
+    printf("%i %f\n", x, y);
+    return 0;
+}
+ 

init.lua

@@ -1,12 +1,11 @@
-local mpp = {}
+mpp = {}
 
-local output = {}
+mpp.c = require "c"
 
 local function process(file)
-    local script = ""
-    local f = io.open(file, "r")
+    local f = assert(io.open(file, "r"))
     coroutine.yield([[
-local output = {}
+output = {}
 function output:literal(x)
     table.insert(self, x)
 end
@@ -14,7 +13,7 @@ function output:expression(f)
     table.insert(self, f)
 end
 ]])
-    
+
     for line in f:lines() do
         if line:find("^%s-" .. mpp.directive) then
             -- Line starts with MPP directive
@@ -46,7 +45,7 @@ end
 
 local function outputmpp(file)
     local generator = coroutine.wrap(function() process(file) end)
-    local f = io.open(file .. ".lua", "w")
+    local f = assert(io.open(file .. ".lua", "w"))
     for line in generator do
         f:write(line)
     end
@@ -55,12 +54,14 @@ end
 function mpp.execute(files)
     local outputs = {}
     for i,file in ipairs(files) do
-        outputmpp(file .. ".mpp")
+        print("executing file " .. file)
+        -- outputmpp(file .. ".mpp")
         outputs[i] = loadmpp(file .. ".mpp")()
     end
     for i,output in ipairs(outputs) do
-        local file = io.open(files[i], "w")
-        for j, o in ipairs(output) do
+        print("outputting file " .. files[i])
+        local file = assert(io.open(files[i], "w"))
+        for _, o in ipairs(output) do
             if type(o) == "string" then
                 file:write(o)
             elseif type(o) == "function" then
@@ -71,6 +72,33 @@ function mpp.execute(files)
     end
 end
 
+function mpp.hook()
+    local hook = {}
+    setmetatable(hook, {
+        __call = function(self, code)
+            table.insert(self, code .. "\n")
+        end
+    })
+    return hook
+end
+
+function mpp.hooks()
+    local hooks = {}
+    setmetatable(hooks, {
+        __index = function(self, key)
+            self[key] = mpp.hook()
+            return self[key]
+        end,
+        __call = function(self, key)
+            output:expression(function()
+                return table.concat(self[key])
+            end)
+        end,
+    })
+    return hooks
+end
+
 
 mpp.directive = "@"
-mpp.execute{ "template.c" }
+-- mpp.execute{ "examples/template.c" }
+mpp.execute{"examples/linkedlist.c"}

template.c

@@ -1,18 +0,0 @@
-#include <stdio.h>
-
-
-
-    int sum_int(int *xs, size_t len) {
-        int sum = 0;
-        for(size_t i = 0; i < len; i++) {
-            sum += xs[i];
-        }
-        return sum;
-    }
-
-int main() {
-    int x = sum_int({strlen("foo"), strlen("bar")});
-    printf("%i\n", x)
-    return 0;
-}
-    

template.c.mpp

@@ -1,23 +0,0 @@
-#include <stdio.h>
-
-@print("foo")
-
-@function sum_t(type, base)
-    @local base = base or 0
-    int sum_$type$($type$ *xs, size_t len) {
-        $type$ sum = $base$;
-        for(size_t i = 0; i < len; i++) {
-            sum += xs[i];
-        }
-        return sum;
-    }
-@end
-
-@sum_t("int")
-
-int main() {
-    int x = sum_int({strlen("foo"), strlen("bar")});
-    printf("%i\n", x)
-    return 0;
-}
-