Initial commit. Just has variable resolution.

Author: Azareal

README.md

@@ -1,2 +1,7 @@
-# SimpleExpressionParser
-A parser for parsing short expressions which can be placed within Discord Bot commands or for incorporating a minimal amount of programming logic in another context.
+# Simple Expression Parser
+
+A parser for parsing simple expressions which can be placed within Discord Bot commands or for incorporating a minimal amount of programming logic in another context. The underlying data is stored as an untyped string ready for it's body to be lazily evaluated.
+
+This fits with Discord's model where the data provided could be anything, and the algorithm might not know what the type is until a specific command or function requests a specific type and it can check to see whether the data satisfies those requirements.
+
+I'm currently in the process of porting this over from Azareal/SajuukBot and turning it into a dependency on that end.

arbitraryFunctions.go

@@ -0,0 +1,23 @@
+package sep
+
+var arbitraryFunctions map[string]func(...string)(string,error) = map[string]func(...string)(string,error){
+"unixtime": func(_ ...string) (string, error) {
+return strconv.FormatInt(time.Now().Unix(),10), nil
+},
+}
+var arbitraryFunctionParams map[string]int = map[string]int{"unixtime":0}
+
+func GetArbitraryFunction(name string) (func(...string)(string,error),bool) {
+res, ok := arbitraryFunctions[name]
+return res, ok
+}
+
+func SetArbitraryFunction(name string, callback func(...string)(string,error), paramCount int) {
+arbitraryFunctions[name] = callback
+arbitraryFunctionParams[name] = paramCount
+}
+
+func HasArbitraryFunction(name string) bool {
+_, ok := arbitraryFunctions[name]
+return ok
+}

sep.go

@@ -0,0 +1,119 @@
+package sep
+
+type Datastore interface {
+SetVar(name, value string) error
+GetVar(name string) (string, bool)
+DeleteVar(name string) error
+}
+
+func ResolveVariable(data string, server_data Datastore) (result string, err error) {
+if len(data) < 3 {
+return "", errors.New("variable name too short x.x")
+}
+if data[0] == '*' {
+data = data[1:]
+}
+
+// Validate the variable and break it up into chunks...
+var parts []string
+var buffer string
+var in_brackets bool
+for _, char := range data {
+if !('a' <= char && char <= 'z') && !('A' <= char && char <= 'Z') && !('0' <= char && char <= '9') && char != '[' && char != ']' && char != '.' && char != '_' && char != '-' {
+return "", errors.New("invalid character in variable name")
+}
+
+if in_brackets {
+if char == ']' {
+if buffer != "" {
+parts = append(parts,buffer)
+buffer = ""
+}
+in_brackets = false
+continue
+}
+}
+
+if char == '[' {
+if buffer != "" {
+parts = append(parts,buffer)
+buffer = ""
+}
+in_brackets = true
+} else if char == '.' {
+if buffer != "" {
+parts = append(parts,buffer)
+buffer = ""
+}
+} else {
+buffer += string(char)
+}
+}
+if buffer != "" {
+parts = append(parts,buffer)
+}
+
+partCount := len(parts)
+data_value, ok := server_data.GetVar(parts[0])
+if !ok {
+return "", errors.New("this variable doesn't exist o.o")
+}
+data_type := detectType(data_value)
+if data_type == "string" && partCount == 2 {
+conv_data, err := strconv.Atoi(parts[1])
+if err != nil {
+return "", errors.New("indices can only be integers x.x")
+}
+if len(data_value) <= conv_data {
+return "", errors.New("index out of range")
+}
+return string(data_value[conv_data]), nil
+}
+
+if partCount > 1 && data_type != "map" && data_type != "list" && data_type != "variable" {
+return "", errors.New("type " + data_type + " cannot have subelements")
+} else {
+return data_value, nil
+}
+
+var n int
+for _, part := range parts {
+if n > 5 {
+return "", errors.New("too many nested subelements")
+}
+switch(data_type) {
+case "map":
+pmap, err := mapParser(data_value)
+if err != nil {
+return "", errors.New("invalid map x.x")
+}
+pdata, ok := pmap[part]
+if !ok {
+return "", errors.New("field does not exist in map")
+}
+data_value = pdata
+case "list":
+plist, err := listParser(data_value)
+if err != nil {
+return "", errors.New("invalid list x.x")
+}
+list_index, err := strconv.Atoi(part)
+if err != nil {
+return "", errors.New("list indices must be integers o.o")
+}
+if len(plist) <= list_index {
+return "", errors.New("index out of range o.o")
+}
+data_value = plist[list_index]
+case "variable":
+data_value, ok := server_data.GetVar(parts[0])
+if !ok {
+return "", errors.New("subvariable doesn't exist o.o")
+}
+data_type = detectType(data_value)
+}
+n++
+}
+
+return data_value, nil
+}