source: branches/2929_PrioritizedGrammarEnumeration/HeuristicLab.Algorithms.DataAnalysis.PGE/3.3/go-code/go-symexpr/parse.go @ 16183

package symexpr

import (
  "fmt"
  "math"
  "strconv"
  "strings"
)

func ParseFunc(text string, varNames []string) Expr {
  expr := parse(text, varNames)
  return expr
}

var itemPrec = map[itemType]int{
  itemAdd:     3,
  itemNeg:     4,
  itemMul:     5,
  itemDiv:     5,
  itemDiv2:    5,
  itemKeyword: 6,
  itemCarrot:  7,
}

func parse(input string, variables []string) Expr {
  L := lex("test", input, variables)
  go L.run()

  // var rules = DefaultRules()

  // fmt.Printf( "Input:     %s\n",input)
  expr := parseExpr("", L, 0)
  // fmt.Printf( "Result:    %v\n\n",expr)
  // simp := expr.Simplify(rules)
  // fmt.Printf( "Output:    %v\n\n",simp)

  return expr
}

func parseExpr(prefix string, L *lexer, p int) Expr {
  // fmt.Printf("%sin-E(%d)\n", prefix, p)
  e := parsePiece(prefix+"  ", L)
  // fmt.Printf("%se(%d): %v\n", prefix, p, e)
  for i := 0; ; i++ {
    var next item
    // fmt.Printf("%sLEX: %v\n", prefix, L.nextToken)

    if L.nextToken.typ == itemNil {
      next = <-L.items
    } else {
      next, L.nextToken.typ = L.nextToken, itemNil
    }
    // fmt.Printf("%snext(%d-%d): %v\n", prefix, p, i, next)
    typ := next.typ
    // fmt.Printf("%sn(%d): %v\n", prefix, p, next)
    if isBinary(typ) && itemPrec[typ] >= p {
      // fmt.Printf("%sbin: %v\n", prefix, next)
      q := itemPrec[typ]
      e2 := parseExpr(prefix+"  ", L, q)
      // fmt.Printf("%se2: %v\n", prefix, e2)
      // fmt.Printf("%snext2(%d-%d): %v\n", prefix, p, i, next2)
      switch typ {
      case itemAdd:
        add := NewAdd()
        add.Insert(e)
        add.Insert(e2)
        e = add
      case itemMul:
        mul := NewMul()
        mul.Insert(e)
        mul.Insert(e2)
        e = mul
      case itemNeg:
        if e == nil {
          neg := NewNeg(e2)
          e = neg
        } else {
          add := NewAdd()
          add.Insert(e)
          add.Insert(NewNeg(e2))
          e = add
        }
      case itemDiv, itemDiv2:
        div := NewDiv(e, e2)
        e = div
      case itemCarrot:
        switch e2.ExprType() {
        case CONSTANTF:
          pow := NewPowI(e, int(e2.(*ConstantF).F))
          e = pow
        default:
          pow := NewPowE(e, e2)
          e = pow
        }
      }
      // fmt.Printf("%snew e: %v\n", prefix, e)
    } else if typ == itemIdentifier && itemPrec[itemMul] >= p {
      L.nextToken = next
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemMul])
      mul := NewMul()
      mul.Insert(e)
      mul.Insert(e2)
      e = mul
      // fmt.Printf("%sid-e: %v\ne2: %v\n", prefix, e, e2)
    } else if typ > itemKeyword && itemPrec[itemKeyword] >= p {
      // fmt.Printf("%skey-e: %v\n", prefix, e)
      L.nextToken = next
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemKeyword])
      mul := NewMul()
      mul.Insert(e)
      mul.Insert(e2)
      e = mul
      // fmt.Printf("%se: %v\ne2: %v\n", prefix, e, e2)
    } else if typ == itemLParen || typ == itemLBrack {
      // consumed '(' or '{'
      e2 := parseExpr(prefix+"  ", L, 0)
      // now consume ')','}'
      var next2 item
      if L.nextToken.typ == itemNil {
        next2 = <-L.items
      } else {
        next2, L.nextToken.typ = L.nextToken, itemNil
      }
      typ2 := next2.typ
      if (typ == itemLParen && typ2 != itemRParen) || (typ == itemLBrack && typ2 != itemRBrack) {
        fmt.Printf("error: expected rhs of %v\n", next2)
      }
      // fmt.Printf("%s(): %v  %v\n", prefix, e, e2)

      mul := NewMul()
      mul.Insert(e)
      mul.Insert(e2)
      e = mul
    } else {
      // fmt.Printf("%selse(%d-%d): %v   %v\n", prefix, p, itemPrec[typ], e, next)
      L.nextToken = next
      break
    }
  }
  // fmt.Printf("%sout-E(%d): %v   %v\n", prefix, p, e, L.nextToken)
  return e
}

func parsePiece(prefix string, L *lexer) Expr {
  // fmt.Printf("%sin-P()\n", prefix)
  var next item
  if L.nextToken.typ == itemNil {
    next = <-L.items
  } else {
    next, L.nextToken.typ = L.nextToken, itemNil
  }
  typ := next.typ
  var e Expr
  // fmt.Printf("%spnxt  %v\n", prefix, next)

  // if isUnary(typ) {
  //  e1 := parseExpr(prefix+"  ", L, 0)
  //  e = NewNeg(e1)
  // } else 
  if typ == itemNeg {
    e1 := parsePiece(prefix+"  ", L)
    e = NewNeg(e1)
  } else if typ == itemLParen || typ == itemLBrack {
    // consumed '(' or '{'
    e = parseExpr(prefix+"  ", L, 0)
    // now consume ')','}'
    var next2 item
    if L.nextToken.typ == itemNil {
      next2 = <-L.items
    } else {
      next2, L.nextToken.typ = L.nextToken, itemNil
    }
    typ2 := next2.typ
    if (typ == itemLParen && typ2 != itemRParen) || (typ == itemLBrack && typ2 != itemRBrack) {
      fmt.Printf("error: expected rhs of %v\n", next2)
    }
    return e
  } else if typ == itemIdentifier { // leaf
    if next.val[0] == 'C' {
      // coefficient
      ipos := strings.Index(next.val, "_") + 1
      index, err := strconv.ParseInt(next.val[ipos:], 0, 64)
      if err != nil {
        fmt.Printf("Error (%v) parsing index in '%s'\n", err, next.val)
      }
      e = NewConstant(int(index))
    } else if next.val[0] == 'X' {
      // variable
      ipos := strings.Index(next.val, "_") + 1
      index, err := strconv.ParseInt(next.val[ipos:], 0, 64)
      if err != nil {
        fmt.Printf("Error (%v) parsing index in '%s'\n", err, next.val)
      }
      return NewVar(int(index))
    } else {
      // is it a named variable ?
      for p, v := range L.vars {
        if next.val == v {
          e = NewVar(p)
          break
        }
      }
      // is it a named constant ?
      if strings.ToLower(next.val) == "pi" {
        e = NewConstantF(math.Pi)
      }

      if e == nil {
        fmt.Printf("UNIMPLEMENTED IDENTIFIER:  %v\n", next)
      }
    }
  } else if typ == itemNumber {
    flt, err := strconv.ParseFloat(next.val, 64)
    if err != nil {
      fmt.Printf("Error (%v) parsing number in '%s'\n", err, next.val)
    }
    e = NewConstantF(flt)

    // } elsi if { // func name...
  } else if typ > itemKeyword {
    // is it a named function
    switch typ {
    case itemSin:
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemKeyword])
      e = NewSin(e2)
    case itemCos:
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemKeyword])
      e = NewCos(e2)
    case itemTan:
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemKeyword])
      e = NewTan(e2)
    case itemAbs:
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemKeyword])
      e = NewAbs(e2)
    case itemSqrt:
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemKeyword])
      e = NewSqrt(e2)
    case itemExp:
      // now consume the '^'
      var next2 item
      if L.nextToken.typ == itemNil {
        next2 = <-L.items
      } else {
        next2, L.nextToken.typ = L.nextToken, itemNil
      }
      typ2 := next2.typ
      if next.val == "e" && typ2 != itemCarrot {
        fmt.Printf("error: expected ^ after 'e', got %v & %v\n", next, next2)
      }
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemCarrot])
      e = NewExp(e2)
    case itemLog:
      e2 := parseExpr(prefix+"  ", L, itemPrec[itemKeyword])
      e = NewLog(e2)
    }

    if e == nil {
      fmt.Printf("Unimplemented Function:  %v\n", next)
    }

  } else { // error
    L.nextToken = next
    e = nil
  }
  // } else if { is it a user defined function

  // fmt.Printf("%sout-P(): %v\n", prefix, e)
  return e
}