Function parseJSONWithStackTracking

pkg/functions/json_stack_parser.go:246–431

parseJSONWithStackTracking parses JSON while tracking the stack structure Returns the error position and any error encountered This implements stack tracking similar to llama.cpp's json_error_locator

(input string, errLoc *JSONErrorLocator)

// Returns the error position and any error encountered
// This implements stack tracking similar to llama.cpp's json_error_locator
func parseJSONWithStackTracking(input string, errLoc *JSONErrorLocator) (int, error) {
	// First, try to parse to get exact error position
	decoder := json.NewDecoder(strings.NewReader(input))
	var test any
	err := decoder.Decode(&test)
	if err != nil {
		errLoc.foundError = true
		errLoc.exceptionMessage = err.Error()

		var errorPos int
		if syntaxErr, ok := err.(*json.SyntaxError); ok {
			errorPos = int(syntaxErr.Offset)
			errLoc.position = errorPos
		} else {
			// Fallback: use end of input
			errorPos = len(input)
			errLoc.position = errorPos
		}

		// Now build the stack by parsing up to the error position
		// This matches llama.cpp's approach of tracking stack during SAX parsing
		partialInput := input
		if errorPos > 0 && errorPos < len(input) {
			partialInput = input[:errorPos]
		}

		// Track stack by parsing character by character up to error
		pos := 0
		inString := false
		escape := false
		keyStart := -1
		keyEnd := -1

		for pos < len(partialInput) {
			ch := partialInput[pos]

			if escape {
				escape = false
				pos++
				continue
			}

			if ch == '\\' {
				escape = true
				pos++
				continue
			}

			if ch == '"' {
				if !inString {
					// Starting a string
					inString = true
					// Check if we're in an object context (expecting a key)
					if len(errLoc.stack) > 0 {
						top := errLoc.stack[len(errLoc.stack)-1]
						if top.Type == JSONStackElementObject {
							// This could be a key
							keyStart = pos + 1 // Start after quote