stred-go

Stred: Streaming Tree Editor. Like sed but for JSON. This is the go implementation
git clone https://shtanton.xyz/git/stred-go.git
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main.go (1279B)

      1 package main
      2 
      3 import (
      4 	"os"
      5 	"bufio"
      6 	"main/walk"
      7 	"main/json"
      8 )
      9 
     10 type Program []Command
     11 
     12 type ProgramState struct {
     13 	path, value, xreg, yreg, zreg walk.ValueList
     14 	in walk.StredReader
     15 	out walk.StredWriter
     16 	program []Command
     17 	pc int
     18 }
     19 
     20 func main() {
     21 	quiet := false
     22 	var input string
     23 	hasInput := false
     24 	
     25 	for i := 1; i < len(os.Args); i += 1 {
     26 		switch os.Args[i] {
     27 			case "-n":
     28 				quiet = true
     29 				continue
     30 		}
     31 		if i < len(os.Args) - 1 {
     32 			panic("Unexpected arguments after program")
     33 		}
     34 		input = os.Args[i]
     35 		hasInput = true
     36 	}
     37 	if !hasInput {
     38 		panic("Missing program")
     39 	}
     40 
     41 	tokens := Lex(input)
     42 	program := Parse(tokens)
     43 
     44 	stdin := bufio.NewReader(os.Stdin)
     45 	stdout := bufio.NewWriter(os.Stdout)
     46 
     47 	state := ProgramState {
     48 		in: json.NewJSONReader(stdin),
     49 		out: json.NewJSONWriter(stdout),
     50 		program: program,
     51 	}
     52 
     53 	for {
     54 		walkItem, err := state.in.Read()
     55 		if err != nil {
     56 			break
     57 		}
     58 		state.value = walkItem.Value
     59 		state.path = walkItem.Path
     60 		state.pc = 0
     61 		for state.pc < len(state.program) {
     62 			state.program[state.pc].exec(&state)
     63 		}
     64 		if !quiet {
     65 			err := state.out.Write(walk.WalkItem {
     66 				Path: state.path,
     67 				Value: state.value,
     68 			})
     69 			if err != nil {
     70 				panic("Error while outputting")
     71 			}
     72 		}
     73 	}
     74 
     75 	state.in.AssertDone()
     76 	state.out.AssertDone()
     77 }