Use another language to call a function: Difference between revisions
Content deleted Content added
Updated to work with Nim 1.4: replaced ".. <text.len" with ".. text.high". Changed compilation command for C. |
Added Wren |
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Now the <code>query-cb</code> function generates callbacks that return -1 to the caller, rather than zero, if aborted by a non-local control transfer such as an exception. |
Now the <code>query-cb</code> function generates callbacks that return -1 to the caller, rather than zero, if aborted by a non-local control transfer such as an exception. |
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=={{header|Wren}}== |
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Currently, the only way to call a Wren function from another language is to embed it in a program written in that language. Therefore, we embed this Wren script: |
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<lang ecmascript>/* query.wren */ |
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class RCQuery { |
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// Both arguments are lists as we need pass by reference here |
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static query(Data, Length) { |
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var s = "Here am I" |
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var sc = s.count |
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if (sc > Length[0]) return 0 // buffer too small |
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for (i in 0...sc) Data[i] = s[i].bytes[0] |
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Length[0] = sc |
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return 1 |
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} |
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}</lang> |
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<br> |
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in the following C program, compile and run: |
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<lang c>#include <stdio.h> |
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#include "wren.h" |
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char *script; |
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WrenVM * vm; |
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WrenForeignMethodFn bindForeignMethod( |
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WrenVM* vm, |
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const char* module, |
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const char* className, |
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bool isStatic, |
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const char* signature) { |
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return NULL; // nothing needed here |
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} |
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static void writeFn(WrenVM* vm, const char* text) { |
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printf("%s", text); |
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} |
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void errorFn(WrenVM* vm, WrenErrorType errorType, const char* module, const int line, const char* msg) { |
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switch (errorType) { |
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case WREN_ERROR_COMPILE: |
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printf("[%s line %d] [Error] %s\n", module, line, msg); |
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break; |
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case WREN_ERROR_STACK_TRACE: |
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printf("[%s line %d] in %s\n", module, line, msg); |
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break; |
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case WREN_ERROR_RUNTIME: |
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printf("[Runtime Error] %s\n", msg); |
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break; |
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} |
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} |
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char *readFile(const char *fileName) { |
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FILE *f = fopen(fileName, "r"); |
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fseek(f, 0, SEEK_END); |
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long fsize = ftell(f); |
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rewind(f); |
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char *script = malloc(fsize + 1); |
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fread(script, 1, fsize, f); |
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fclose(f); |
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script[fsize] = 0; |
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return script; |
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} |
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int configWrenVM() { |
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WrenConfiguration config; |
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wrenInitConfiguration(&config); |
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config.writeFn = &writeFn; |
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config.errorFn = &errorFn; |
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config.bindForeignMethodFn = &bindForeignMethod; |
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vm = wrenNewVM(&config); |
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const char* module = "main"; |
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const char* fileName = "query.wren"; |
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script = readFile(fileName); |
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WrenInterpretResult result = wrenInterpret(vm, module, script); |
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switch (result) { |
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case WREN_RESULT_COMPILE_ERROR: |
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printf("Compile Error!\n"); |
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return -1; |
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case WREN_RESULT_RUNTIME_ERROR: |
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printf("Runtime Error!\n"); |
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return -1; |
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case WREN_RESULT_SUCCESS: |
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break; |
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} |
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return 0; |
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} |
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int Query(char *Data, size_t *Length) { |
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int i, r; |
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wrenEnsureSlots(vm, 4); |
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// create list for Data, fill with zeros and put in slot 1 |
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wrenSetSlotNewList(vm, 1); |
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wrenSetSlotDouble(vm, 2, 0.0); |
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for (i = 0; i < *Length; ++i) wrenInsertInList(vm, 1, i, 2); |
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// create list for Length and put in slot 2 |
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wrenSetSlotNewList(vm, 2); |
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wrenSetSlotDouble(vm, 3, (double)*Length); |
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wrenInsertInList(vm, 2, 0, 3); |
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// get handle to Wren's query method |
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WrenHandle* method = wrenMakeCallHandle(vm, "query(_,_)"); |
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// get its class and put in slot 0 |
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wrenGetVariable(vm, "main", "RCQuery", 0); |
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// call the Wren method |
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wrenCall(vm, method); |
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// get the result and check it's 1 |
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r = (int)wrenGetSlotDouble(vm, 0); |
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if (r) { |
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// get the length of the string from slot 2 |
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wrenGetListElement(vm, 2, 0, 3); |
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*Length = (int)wrenGetSlotDouble(vm, 3); |
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// copy the bytes from the list in slot 1 to the C buffer |
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for (i = 0; i < *Length; ++i) { |
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wrenGetListElement(vm, 1, i, 3); |
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Data[i] = (char)wrenGetSlotDouble(vm, 3); |
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} |
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} |
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return r; |
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} |
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int main() { |
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int e = configWrenVM(); |
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if (!e) { |
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char Buffer [1024]; |
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size_t Size = sizeof(Buffer); |
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if (0 == Query(Buffer, &Size)) { |
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printf ("failed to call Query\n"); |
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e = 1; |
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} else { |
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char * Ptr = Buffer; |
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while (Size-- > 0) putchar (*Ptr++); |
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putchar ('\n'); |
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} |
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} |
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wrenFreeVM(vm); |
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free(script); |
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return e; |
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}</lang> |
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{{out}} |
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<pre> |
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Here am I |
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</pre> |
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=={{header|zkl}}== |
=={{header|zkl}}== |